Removal of sizing material from reinforcing fibers for recycling of reinforcing fibers

ABSTRACT

Processing sized fiber products to recover reinforcing fibers by removing fiber sizing material from the reinforcing fibers. The processing includes first treating the sized fiber product with a normally-liquid first solvent for fiber sizing material followed by removal of the first solvent from the first solid residue including reinforcing fibers. The removal of the first solvent from the continuous reinforcing fibers may include heating the fibers and/or second treating the first solid residue with a normally-gaseous material contacted with the solid residue under conditions of temperature and pressure at which the normally-gaseous material is in a liquid or supercritical fluid form. The processing may be performed in a continuous manner to recover the continuous reinforcing fibers in a continuous form.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional App. No.62/568,170 filed on Oct. 4, 2017 entitled “REMOVAL OF SIZING MATERIALFROM REINFORCING FIBERS FOR RECYCLING OF REINFORCING FIBERS,” theentirety of which is incorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to recovery of reinforcing fibers, such as carbonor other fibers, for recycling of such reinforcing fibers.

BACKGROUND OF THE INVENTION

Carbon fiber-reinforced polymers (CFRPs) are composite materialsincluding carbon fibers as reinforcing agents bound in a matrix,typically a matrix of a plastic composition. The reinforcing fibers usedin CFRPs typically include fiber sizing material on the surface of thefibers to, among other purposes, promote coupling with the matrix. CFRPsare used in a variety of consumer and industrial products. A high costof virgin carbon fibers of industrial or commercial grade limitsutilization in a broader-range of end-user applications, includinglimiting broader use in automotive and transportation sectors wherethere is significant potential for expanded use.

There are a variety of intermediate forms of reinforcingfiber-containing products in which reinforcing fibers, and includingcarbon fibers, may be present in the industrial chain between initialmanufacture of the reinforcing fibers and a final CFRP in a finalproduct form. For example, following manufacturing of the reinforcingfibers, the reinforcing fibers may be covered with a thin layer of othermaterial or materials to protect the reinforcing fibers from damage ordegradation during handling, shipping, storage and manufactureoperations and/or for enhanced performance interaction with materialsof, or precursors for, the matrix of the intended final CFRP productform. Such a layer is often referred to as “fiber sizing”, and amaterial of such a layer may be referred to as a fiber sizing material.The process of applying fiber sizing may be incorporated into anintegrated manufacturing operation in which fiber sizing is applied tothe virgin reinforcing fibers soon after they are formed in themanufacture operation, for example to provide immediate protection tothe reinforcing fibers and in a form compatible with the final intendedmatrix for a CFRP. Alternatively, the virgin reinforcing fibers may bestored and/or shipped in the virgin form for later processing to applyfiber sizing in a separate manufacture operation. Such reinforcingfibers following application of fiber sizing may be referred to as sizedreinforcing fibers, and products with the sized reinforcing fibers priorto addition of a matrix or matrix precursor for a CFRP may be referredto a sized fiber products. Sized fiber products may be in a productform, for example, individual strands, tow (e.g., untwisted bundle),yarn (e.g., twisted bundle) or mat or sheet form (e.g., woven ornonwoven forms). Virgin fibers, without fiber sizing applied, may alsobe prepared into such product forms. Such product forms may be furtherprocessed, in an integrated manufacturing operation or a separatemanufacturing operation, to add material for a matrix to form a CFRP,which may be in the form of the final matrix (e.g. thermoplastic matrixcompositions) or in a preliminary resin composition form (e.g., uncuredthermoset resin), and may be referred to as a preliminary CFRP, whichwill typically have the reinforcing fibers in the same general geometricarrangement (e.g., tow, yarn, sheet or mat form) as in the form prior toadding material of the matrix. A preliminary CFRP with an uncuredthermoset resin material for a matrix is often referred to as a prepreg.Such a preliminary CFRPs may be used in a final product manufacturingoperation in which the CFRP is shaped into and set in a desired finalproduct form (e.g., with heating followed by cooling in the case of athermoplastic matrix and curing in the case of a thermoset matrix). Sucha final product form may be referred to as a final CFRP. Such sizedreinforcing fiber products, preliminary CFRPs and final CFRPs are allexamples of reinforcing fiber-containing products, which include thereinforcing fibers in combination with one or more other materials(e.g., fiber sizing material and/or preliminary or final matrixmaterial).

Even with the high cost of virgin carbon fibers, a significant quantityof CFRPs and/or the carbon fibers therein, end up as waste. It is commonin CFRP applications for material trim and scrap waste to amount toabout 30% or more of finished part weight. In addition, raw materialsused in manufacturing of products from fiber-reinforced compositesincluding, for example, reinforcing fibers with fiber sizing orfiber-reinforced composites (e.g., prepreg materials) used in productionof CFRPs may have a limited shelf-life prior to use in manufacturing.Often times, the raw materials expire prior to being utilized in amanufacturing process. Manufacturing waste, whether in the form ofmaterial trim, scrap, or expired product, is often incinerated or sentto a landfill resulting in additional waste disposal costs andsignificant lost raw material value.

Trim and scrap waste represent a possible resource for recycled carbonfibers, and attempts have been made to process such trim and scrap wasteto recover carbon fibers for recycling. However, effectively freeingcarbon fibers for recovery from CFRP matrix and/or sizing material hasproven difficult, with a result being that recycling processing hastended to be expensive and/or to result in significant degradation ofcarbon fiber properties, significantly limiting utility of recycling asa source of carbon fibers for a range of possible applications.Moreover, as will be discussed in greater detail below, recyclingprocessing has also tended to result in processed carbon fibers of alesser or degraded form as compared to the feedstock for such processes.For instance, during recycling, fibers often are severed, tangled, orfrayed, which limit the available forms for recycled carbon fibercomposites.

One recycling technique involves subjecting waste materials topyrolysis. This technique utilizes high temperatures to decomposepolymeric matrix while attempting to leave the reinforcing fibersintact. The carbon fibers recovered from this processing often have ashort fiber length with limited potential for reuse in new products.Also, pyrolysis, as a process option, has significant limitations withrespect to intensive energy requirements, high processing costs, andpotential for negative environmental impact due to emission of pyrolysisby-products.

Another type of recycling technique uses chemical agents to chemicallyreact with and degrade, and break down the polymeric matrix (sometimesreferred to as depolymerization) to degradation products that may beseparated from the carbon fibers, such as by dissolution of thedegradation products into a solvent. Such processes tend to be expensiveand may also degrade carbon fiber properties.

In addition, while the foregoing techniques have generally beenconsidered for use in recycling of trim and scrap waste that includediscontinuous reinforcing fibers, certain sources of recyclable materialinclude continuous fibers such as continuous prepreg sheets orcontinuous prepreg tow. These materials in the continuous form mayprovide advantages for use in manufacturing processes and/or in finishedproducts produced using the continuous forms. For example, productsmanufactured with unidirectional fiber reinforced sheets or tow materialmay provide enhanced directionalized part performance. As such,recycling techniques applicable to discontinuous fibers, such as thoseresulting from trim and scrap waste, may require severing, tangling, orfraying fibers which results in degradation of the continuous form, thusdegrading the resulting recycled fiber product.

A need exists for improved processes to recover carbon fibers forrecycling in a manner that increases the range of applications in whichrecycled carbon fibers may be technically and economically suitable foruse. Moreover, an approach that maintains a continuous form of carbonfibers from waste materials is needed.

SUMMARY OF THE INVENTION

It has been found that many CFRP forms may be advantageously processedto recover high quality carbon fibers using a solvent-based process thatdoes not depend upon chemical decompositions of the matrix of the CFRP.Advantageous variations on the solvent-based processing includeeffective separation and removal of residual solvent and finish cleaningof recovered carbon fibers, for example to remove remaining residualmatrix material and/or to remove remaining fiber sizing material. Thetechniques disclosed herein may be useful for processing CFRP that is ina prepreg form, such as including an uncured thermoset resin matrix inwhich the carbon fibers are held. There is a significant quantity ofsuch composite prepreg waste that is generated in the form of scrap andtrim waste, known as offal. Additional scrap waste results duringmanufacturing of product that fails to meet specification and expiredprepreg composite product that is not used within a specified shelf-lifefor the product. In addition, the techniques disclosed herein may beused for processing of sized fiber products, whether in a matrix or inthe absence of a matrix, to remove fiber sizing from the reinforcingfibers.

The solvent-based processing disclosed herein significantly reduces bothprocessing complexity and energy requirements relative to pyrolysis andchemical depolymerization processes. This solvent-based processing isalso applicable to composites including reinforcing fibers other thancarbon fibers held in a matrix or other reinforcing fibers having sizingmaterial in the absence of matrix, but the disclosure herein is madewith reference primarily to carbon reinforcing fibers held in a matrix,although the principles disclosed herein also apply to recovery andrecycling of other reinforcing fibers, whether in a matrix or in theabsence of a matrix, as described below. For brevity, reinforcing fibersare often referred to herein simply as fibers. The solvent-basedprocesses contemplated herein may also be advantageously used to recoverand/or recycle fibers in continuous form, which may provide increasedvalue and utility for new products to be manufactured using the recycledfibers. That is, continuous fiber-reinforced composites or continuoussized fiber product in the absence of a matrix may be recycled tomaintain the fibers in the continuous form, thus improving the value andutility of the resulting recycled fibers.

In turn, the present disclosure describes a number of embodiments ofmethods that may be applicable to recovery and/or recycling ofreinforcing fibers therefrom. The embodiments described herein mayincorporate processing as described in PCT App. No. PCT/US2016/024956entitled “RECOVERY OF REINFORCING FIBERS FROM FIBER-REINFORCEDCOMPOSITES” filed on Mar. 30, 2016, which is incorporated by referencein its entirety. Specifically, the embodiments described herein mayapply a process of solvent-based processing to a fiber-reinforcedcomposite or sized fiber product in the absence of a matrix.

In one particular application of the techniques described herein, asized fiber product may be processed to remove fiber sizing materialfrom reinforcing fibers of the sized fiber product. As used herein,fiber sizing material, fiber sizing, sizing material, or simply sizingmay each be used to refer to fiber sizing material generally whetherdisposed on the surface of a reinforcing fiber or separate from anyreinforcing fiber. Sized fiber or sized fiber product may refer to thearrangement in which fiber sizing material is applied to the surface ofthe reinforcing fibers. In this regard, a sized fiber product may referto a product form that at least includes reinforcing fibers and fibersizing material disposed on the surface of the reinforcing fibers. Thefiber sizing material may be applied as a coating to the surface of thereinforcing fibers to form a sized fiber product. Such fiber sizing isoften applied to carbon fibers, although fiber sizing may also be usedin relation to other reinforcing fibers to produce sized fiber products.Fiber sizing material applied to the surface of reinforcing fibers in asized fiber product may, for example, provide one or more of thefollowing functions: protecting the fiber, preventing fiberagglomeration, improving processability of the fibers, and acting as acompatibility agent to improve dispersibility in and/or binding withmatrix material. A sized fiber product may be provided in a continuousform containing continuous reinforcing fibers and may be processed asdescribed herein in relation to processing composites in a continuousform.

For many recycling applications, it is desirable to clean thereinforcing fibers of some or all residual matrix material and/or sizingmaterial. In other applications, such residual matrix material and/orsome retained fiber sizing material may not be a problem. In someapplications, sized fiber products may be provided in the absence of amatrix for recycling or recovery of the reinforcing fibers by removingthe fiber sizing material from the reinforcing fibers. For higher valuerecycling applications, it may be preferred to remove both residualmatrix material and fiber sizing material to provide clean fibers, whichmay then be processed to add new sizing to the fibers if desired.

For purposes of this disclosure, fiber sizing is not considered a partof either a reinforcing fiber or a matrix, and is separate from each ofthose terms. Rather, to the extent that reinforcing fibers of afiber-reinforced composition are coated with fiber sizing, that fibersizing is a separate material from the reinforcing fibers and from thematrix, even though the fiber sizing may provide a binding intermediatebetween the reinforcing fiber and the matrix. Reference to sized fiberproduct refers only to the reinforcing fibers and sizing material,although it may be appreciated that such a sized fiber product may beincluded in a composite including a matrix. In other applications, asized fiber product may be processed in the absence of a matrix toremove the fiber sizing material from the reinforcing fibers. Asdescribed below, processing to remove the fiber sizing material from thesized fiber product may be according to the disclosure herein thatdescribes removal of a matrix and/or fiber sizing from reinforcingfibers. Any disclosure provided herein that refers to processing of afiber-reinforced composite for removal of a matrix may also be used inconjunction with a sized fiber product in the absence of a matrix toremove fiber sizing material from reinforcing fibers.

Accordingly, a first aspect of the present disclosure includes a methodfor processing a sized fiber product comprising reinforcing fibers withfiber sizing material on the reinforcing fibers in the absence of amatrix for recovery of the reinforcing fibers from the sized fiberproduct. The method includes first treating the sized fiber productcomprising reinforcing fibers with fiber sizing material on thereinforcing fibers in the absence of a matrix with a normally-liquidfirst solvent for the fiber sizing material to prepare a first treatedsolid residue comprising the reinforcing fibers. The first treatingincludes contacting the sized fiber product with the first solvent andfirst dissolving at least a majority by weight of the fiber sizingmaterial into the first solvent. The method also includes, after thefirst treating, second treating at least a portion of the first treatedsolid residue comprising the reinforcing fibers to remove a residualportion of the first solvent associated with the first solid residue andprepare second treated solid residue.

A number of feature refinements and additional features are applicableto the first aspect. These feature refinements and additional featuresmay be used individually or in any combination. As such, each of thefollowing features that will be discussed may be, but are not requiredto be, used with any other feature or combination of features of thefirst aspect.

For instance, in an embodiment, the second treating may include heatingthe residual portion of the first solvent in the presence of thereinforcing fibers to volatilize the residual portion of the firstsolvent. In another embodiment, the second treating may includecontacting at least a portion of the first treated solid residuecomprising the reinforcing fibers with a normally-gaseous material toprepare second treated solid residue. The second treating includescontacting the at least a portion of the first treated solid residuewith the normally-gaseous material under conditions of temperature andpressure at which the normally-gaseous material is in a form of a liquidor supercritical fluid.

In an embodiment, the method may include a third treating after thesecond treating. Such third treating may include further treating atleast a portion of the second treated solid residue, including thereinforcing fibers, by first converting a normally-gaseous substance incontact with such second treated solid residue from a fluid form to asolid form. After the normally-gaseous substance is in the solid form,the third treating includes second converting of the normally-gaseoussubstance from the solid form to a gaseous form. Such third treating maysignificantly assist dislodgment from the reinforcing fibers of residualmaterial that may include fiber sizing material. During the secondconverting, rapidly expanding gas may mechanically dislodge significantresidual fiber sizing material from the fibers. Such second convertingmay involve rapid sublimation from the solid form to the gaseous form.

The first converting of such third treating may include reducing thetemperature of the normally-gaseous substance from a higher firsttemperature to a reduced second temperature. Such a higher temperaturemay often be at least 0° C., at least 5° C., at least 10° C., at least15° C., or at least 20° C.; although often the higher temperature may beno higher than 100° C., no higher than 50° C., no higher than 40° C., orno higher than 30° C. The higher temperature may typically be ambienttemperature. Such a reduced temperature may be −40° C. or lower, −50° C.or lower, −56.6° C. or lower, −60° C. or lower, or −70° C. or lower. Atsuch a higher first temperature, the normally-gaseous substance is underconditions of temperature and pressure at which the normally-gaseoussubstance is in the form of a gas, liquid or supercritical fluid, andpreferably a liquid. At the reduced temperature, the normally-gaseoussubstance is under conditions of temperature and pressure at which thenormally-gaseous material is in the form of a solid. In someimplementations, the conditions at the reduced temperature includeambient pressure (approximately one bar). In some implementations, theconditions at the higher temperature include elevated pressure relativeto ambient pressure (e.g., higher than atmospheric pressure).

The first converting may include significantly reducing pressure of thenormally-gaseous substance from an elevated pressure, and reducing thetemperature of the normally-gaseous substance may include gas expansioncooling as the pressure is reduced. The elevated pressure may be atleast 3.0 MPa, at least 3.5 MPa, at least 4 MPa, at least 5 MPa, atleast 7 MPa, at least 7.39 MPa, or at least 7.5 MPa. The elevatedpressure may be a pressure as described below for the pressure duringthe second treating in an application where the second treating includescontacting the first treated solid residue with a normally-gaseousmaterial in liquid or supercritical fluid form. The reducing pressuremay include reducing the pressure of the normally-gaseous substance fromthe elevated pressure to a lower pressure of 1 MPa or lower, 0.750 MPaor lower, 0.5 MPa or lower, 0.250 MPa or lower, or even 0.15 MPa orlower, or even to about ambient pressure (approximately one bar). Insome preferred implementations when using carbon dioxide as thenormally-gaseous substance, the reducing temperature may includereducing the temperature to a temperature at or below the triple pointfor carbon dioxide (−56.6° C.) and preferably even lower (e.g., at orbelow −60° C.), or even to a temperature at or below the normalsublimation point of carbon dioxide (−78.5° C.). Similarly, when usingcarbon dioxide as the normally-gaseous substance, such a lower pressureof such a reducing pressure step may preferably be at or below thetriple point pressure of carbon dioxide (0.518 MPa), and more preferablybelow such a triple point pressure (e.g., at or close to ambientpressure).

The second converting preferably includes rapidly converting thenormally-gaseous substance from the solid form to the gaseous form in ashort time period for effective dislodgment of residual fiber sizingmaterial. Such a time period may be, for example, no greater than 120seconds, no greater than 60 seconds, no greater than 45 seconds, nogreater than 30 seconds, no greater than 20 seconds, no greater than 15seconds, no greater than 10 seconds, or no greater than 5 seconds,although such time period may often be at least 1 second. The secondconverting may include contacting second treated solid residue with aheat transfer fluid at a greater temperature than the reducedtemperature of the solid form of the normally-gaseous material, forexample, with the temperature of the heat transfer fluid immediatelyprior to contacting with the second treated solid residue being at least5° C. greater than, at least 10° C. greater than, at least 25° C.greater than, at least 50° C. greater than, at least 75° C. greaterthan, at least 100° C. greater than or even at least 150° C. greaterthan the reduced temperature, although often also being not more than225° C. greater than the reduced temperature. The heat transfer fluidmay be in the form of a gas, liquid, or a supercritical fluid whencontacted with the second treated solid residue and the solid form ofthe normally-gaseous material. Some example heat transfer fluids includean oil, liquid water, steam (saturated or superheated), air, nitrogen,and carbon dioxide. The second converting may include rapid sublimationof the normally-gaseous substance from the solid form.

The normally-gaseous substance of the third treating may be anynormally-gaseous material that may be subjected to such first and secondconverting. Some example materials for the normally-gaseous substancefor the third treating include any of the normally-gaseous materials, orcombinations thereof, identified for the normally-gaseous material ofthe second treating that includes contacting the first residual solidwith a normally-gaseous material in liquid or supercritical fluid form,with carbon dioxide being preferred for use in both the second treatingand the third treating. The normally-gaseous substance of the thirdtreating may be of the same composition or a different composition thanthe normally-gaseous material of the second treating of the firstresidual solid with a normally-gaseous material in liquid orsupercritical fluid form. In some preferred implementations, thenormally-gaseous substance of the third treating is the same as thenormally-gaseous material of the second treating that includescontacting the first residual solid with a normally-gaseous material inliquid or supercritical fluid form, and in more preferredimplementations, the normally-gaseous substance of the third treating ismade up of some or all of the normally-gaseous material of the secondtreating that remains in contact with the second treated solid residueat the conclusion of the second treating (e.g., carbon-dioxide remainingfrom the second treating).

The second treated solid residue resulting from the second treatingshould preferably be mostly free from the presence of the first solventand more preferably should be essentially free of the presence of thefirst solvent, or stated in a different way the second treated solidresidue is preferably essentially in a completely dried state relativeto the first solvent. The second treated solid residue will alsotypically have a very high content of the reinforcing fibers, but maystill contain some minor amounts of other materials (e.g., residualfiber sizing material). The reinforcing fibers may, for example make upat least 90 weight percent, at least 95 weight percent, at least 98weight percent, or even at least 99 weight percent or more (e.g.,essentially 100 weight percent) of the second treated solid residue. Thesecond treated solid residue may have essentially the same compositionas the first treated solid residue, but dried of the first solvent, forexample, when the second treating is essentially in the absence of anysignificant dissolution of fiber sizing into the liquid or supercriticalfluid form of the normally-gaseous material. Alternatively, the secondtreated solid residue may have a higher weight percentage of reinforcingfibers and a correspondingly lower weight percentage of other materials,for example when the liquid or supercritical fluid form of thenormally-gaseous material dissolves some portion of fiber sizingmaterial.

When the method includes the third treating, a product of such thirdtreating may be third treated solid residue, which may be a cleanedproduct after separating dislodged pieces of fiber sizing, for exampleby flushing them away with heat transfer fluid, effluent of thenormally-gaseous substance or another flushing fluid. Such a cleanedproduct may include mostly or even essentially all reinforcing fibersand preferably with a reduced content or even essentially free ofresidual fiber sizing. The reinforcing fibers may make up at least 90weight percent, at least 93 weight percent, at least 96 weight percent,at least 98 weight percent, at least 99 weight percent, at least 99.5weight percent, or at least 99.8 weight percent of such a cleanedproduct.

In preferred implementations, a majority or even most of the fibersizing material is dissolved into the first solvent during the firsttreating. For example, the first treating may include dissolving intothe first solvent at least 60 weight percent, at least 70 weightpercent, at least 80 weight percent, at least 90 weight percent, atleast 95 weight percent, at least 97 weight percent, at least 98 weightpercent or even at least 99 weight percent or more of the fiber sizingmaterial into the first solvent during the first treating. In someimplementations, the first treating may include dissolving into thefirst solvent all (100 weight percent) or essentially all of the fibersizing material. In some implementations, the first treating may includedissolving into the first solvent up to 99.8 weight percent, up to 99.5weight percent, up to 99 weight percent, up to 98 weight percent, up to97 weight percent, up to 95 weight percent or up to 90 weight percent ofthe fiber sizing material.

The dissolving during the first treating may be conducted at anyconvenient temperature (e.g., temperature of the first solvent duringthe dissolving), but typically at a temperature that is lower than anormal boiling point of the first solvent. In some implementations thetemperature may be in a temperature range having a lower limit of 0° C.,10° C., 15° C., or 20° C.; and an upper limit of 40° C., 35° C., or 30°C. In some implementations, the temperature may be essentially ambienttemperature. The dissolving may be conducted under an elevated pressure,but is often conducted at ambient pressure (approximately one bar). Insome implementations, the pressure during the dissolving may be in arange having a lower limit of 0.08 MPa, 0.1 MPa, 0.15 MPa, or 0.2 MPa;and an upper limit of 2 MPa, 1 MPa, 0.7 MPa, 0.5 MPa, or 0.3 MPa.

A sized fiber product may include surface treatments on the fiber or onthe fiber sizing material, dispersing agents, and compatibilizingagents. In some preferred implementations, the amount of any one or ofall components other than the reinforcing fibers make up no more than 10weight percent, no more than 5 weight percent, no more than 3 weightpercent, or no more than 1 weight percent of the sized fiber product.The fiber sizing material may include a member selected from the groupconsisting of maleic anhydride grafted polypropylene, polyurethane,epoxy, polyamide, polyimide, phenoxy ethylene maleic anhydride,butadiene maleic anhydride, ethylene acrylic acid, acrylic dispersions,a silane compound, or combinations thereof.

The reinforcing fibers may include fibers of a single type or mayinclude fibers of multiple different types. The reinforcing fibers maybe limited to including only one of the following or any number of twoor more of the following types of fibers: carbon fibers (preferred),carbon nanotube fibers, aramid fibers, glass fibers, boron fibers,basalt fibers, high-modulus polyethylene fibers, polyp-phenylene-2,6-benzobisoxazole fibers, quartz fibers, ceramic fibers,stainless steel fibers, titanium fibers, copper fibers, nickel fibers,metal coated fibers (e.g., coated with silver, gold, ruthenium,Miralloy®, alloys, etc.), natural fibers and mineral fibers. The fibersmay include only a single material phase (e.g., fibers composed of asingle, uniform material) or may be multi-phasic structures (e.g., metalcoated fibers including a core of one material phase and different metalcoating material phase). Such fibers will typically have a diameter in amicro-size range (e.g., 100 microns or smaller) or even a nano-sizerange (e.g., smaller than one micron).

The first solvent may be any liquid composition that is a solvent formaterial of the fiber sizing material, and that preferably is chemicallynonreactive, and more preferably chemically inert, with respect to thereinforcing fibers. While the present aspect relates to processing of asized fiber material in the absence of a matrix, it may be appreciatedthat the first solvent may also be a solvent for a matrix of afiber-reinforced composite as described herein. In this regard, eitheror both of a sized fiber product in the absence of a matrix or afiber-reinforced composite including a matrix may be processed accordingto the same technique provided herein. This may be advantageous asequipment setups, chemical baths, or the like used in processingdescribed herein may not need to be changed between processing a sizedfiber product in the absence of a matrix and a fiber-reinforcedcomposite held in a matrix.

By a material being chemically nonreactive with respect to anothermaterial, it is meant that the material, under conditions of temperatureand pressure during the relevant processing, is essentially notchemically reactive with the other material. By a material beingchemically inert to another material, it is meant that the material,under conditions of temperature and pressure during the relevantprocessing, is essentially not chemically reactive with the othermaterial and is essentially not a solvent for the other material. Thefirst solvent may be a single component or may be a multi-componentmixture of multiple components that together provide the desiredsolvating properties for dissolving fiber sizing material. The firstsolvent may include any one or any combination of two or more of thefollowing, with or without other additional components: acetone,methylene chloride (preferred), methoxy-nonafluorobutane,2-methyltetrahydrofuran, tetrahydrofuran, tetrachloroethylene, n-propylbromide, dimethyl sulfoxide, polyolester oil, esters, ethers, acetates,acids, alkalis, amines, ketones, glycol ethers, glycol ether esters,ether esters, ester-alcohols, alcohols, halogenated hydrocarbons,paraffinic hydrocarbons, aliphatic hydrocarbons, aromatic hydrocarbons,and combinations thereof.

In some preferred implementations, a result of the first treating isthat most of the fiber sizing material has been dissolved into the firstsolvent and the first treated solid residue is made up mostly ofreinforcing fibers. For example reinforcing fibers may make at least 70weight percent, at least 80 weight percent, at least 90 weight percent,at least 95 weight percent, at least 98 weight percent or even at least99 weight percent or more (but often less than 100 weight percent) ofthe first treated solid residue. The first treated solid residue mayinclude minor quantities of other material, other than the reinforcingfibers, for example some residual fiber sizing material (e.g.,undissolved or re-precipitated during processing).

The method may typically include prior to the second treating (i.e., aspart of processing during the first treating or between the firsttreating and the second treating) separating first solvent loaded withdissolved fiber sizing material (rich first solvent) from the firsttreated solid residue. Such separation may include any liquid-solidseparation technique, for example any one or more of the following:settling and decantation (including accelerated settling throughcentrifugal extraction), cyclone separation, and/or filtration.Filtration may, for example, involve filtration in which first solventpasses through filter medium as filtrate and first treated solid residueremains with retentate. Preferably a majority or even most of the firstsolvent will be separated from the first treated solid residue by suchprocessing. However, even after such filtration or other liquid-solidseparation, the first treated solid residue may still be in the presenceof some amount of residual first solvent, which is problematic in termsof practical utility of the reinforced fibers in the first treated solidresidue. In preferred processing, a normally-gaseous material in theliquid or supercritical form used in the second treating involving sucha material acts as a second solvent (of a different composition than thefirst solvent) during the second treating to dissolve some, andpreferably essentially all, such residual first solvent that remains inthe presence of the first treated solid residue. Such liquid orsupercritical fluid form may also have some solvating capability fordissolving some amount of the fiber sizing material in the first treatedsolid residue that may remain in the first treated solid residue.However, it is typically preferred that such liquid or supercriticalfluid form be a good solvent for the first solvent, with dissolution ofadditional residual fiber sizing material being a secondary, but notnecessary benefit if available. It will be understood that terms such as“first solvent” and “second solvent” are for convenience of referenceand do not mean or imply that processing necessarily includes more thanone solvent or any particular number of different solvents, except asstated.

The normally-gaseous material may be comprised of a singlenormally-gaseous component or a normally-gaseous mixture of multipledifferent components wherein the mixture is normally-gaseous, whether ornot all of the components of such mixture are normally-gaseousindividually. Preferably, such a normally-gaseous mixture is made upessentially of only components that are each individuallynormally-gaseous. By a material being normally-gaseous it is meant thematerial is in the form of a gas at conditions of 0.1 MPa pressure and25° C. temperature. By a material being normally-liquid it is meant thematerial is in the form of a liquid at conditions of 0.1 MPa pressureand 25° C. temperature. The terms material and substance are genericterms for compositions that include one or more than one component, andthe terms are used interchangeably herein. Different ones of these termsmay be used in different portions of this disclosure for convenience ofreference. Some example materials that may be or may be a part of thenormally-gaseous material include any one or any combination of two ormore of the following, with or without the presence of any othercomponent or components: carbon dioxide, 1,1,1,2-tetrafluoroethane,difluoromethane, pentafluoroethane, and combinations thereof. Inpreferred implementations, the normally-gaseous material is chemicallynonreactive, and even more preferably is chemically inert, with respectto the reinforcing fibers. A preferred normally-gaseous material for thesecond treating comprises carbon dioxide, and more preferably consistsessentially of carbon dioxide.

As noted, during the contacting of the second treating with anormally-gaseous material is in the form of a liquid or a supercriticalfluid. The pressure at which such contacting is conducted, may often bewithin a range having a lower limit of 2 MPa, 3 MPa, 3.5 MPa, 4 MPa, 5MPa, 7 MPa, 7.39 MPa, or 7.5 MPa; and an upper limit of 69 MPa, 50 MPa,40 MPa, 30 MPa, 20 MPa, or 10 MPa, and such a range is particularlypreferred in the case of carbon dioxide as the normally-gaseousmaterial. The temperature of the contacting of the second treating mayoften be within a range having a lower limit of 0° C., 10° C., 13° C.,15° C., 20° C., or 30° C. and an upper limit of 175° C., 150° C., 125°C., 100° C., 75° C., 60° C., 50° C., or 40° C., provided that the upperlimit is higher than the lower limit, and such a range is particularlypreferred in the case of carbon dioxide as the normally-gaseousmaterial. As will be appreciated, a supercritical fluid refers to afluid at a temperature and pressure above the critical temperature andcritical pressure for the material, for example at a temperature above31.1° C. and a pressure above 72.9 atmospheres (7.39 MPa) in the case ofcarbon dioxide as the normally-gaseous material.

As stated above, the sized fiber product may be provided for processingin the absence of a matrix. Such a matrix may be provided as a plasticmaterial or plastic compound that holds reinforcing fibers in afiber-reinforced composite. A sized fiber product may be provided withreinforcing fibers having fiber sizing material on the surface of thefibers that has not had a matrix applied thereto or in which a matrixhas been removed leaving the reinforcing fibers and sizing material. Theterms plastic material and plastic composition are used interchangeablyherein. By the matrix of a fiber-reinforced composite being a plasticmaterial it is meant a “set” plastic composition, which may be athermoplastic material (reversibly set by thermal processing) or may bea cured thermoset composition (irreversibly set chemically, alsoreferred to as a “thermoset”). By “precursor”, “precursor composition”,“thermoset precursor composition” or the like for a plastic material itis meant a preliminary composition that is to undergo additionalchemical reaction to prepare that plastic material, which may be forexample a final cured thermoset composition for a final thermosetmatrix. Such a precursor may be an uncured thermoset resin (which mayalso be referred to as an uncured thermoset resin composition orthermoset prepolymer composition). As used herein, an “uncured”composition refers to precursor that has not been subjected to curing orhas been only partially cured, such that additional curing is requiredto prepare the final plastic composition (e.g., to prepare a finalthermoset). In contrast, a “cured” composition refers to such a finalplastic composition after completion of all curing operations (e.g., afinal thermoset). Such a precursor composition is typically malleableand re-formable in shape to at least some degree, whereas a curedthermoset composition may be irreversibly chemically set and maytypically not be malleable or re-formable in shape (is permanentlyshaped). Curing typically involves one or more chemical reactions, oftenincluding cross-linking. A composite including reinforcing fibers and amatrix of such a precursor for a plastic material may be referred to asa “thermoset prepreg composite”, a “prepreg composite” or even simply as“prepreg”. Curing of a precursor composition may be induced or caused bya variety of stimuli depending on the composition, for example throughthe application of heat and/or radiation. By “plastic material” or“plastic composition” it is meant a composition composed predominantlyof polymer components, but which may include minor amounts of variousadditives, for example, plasticizer or other additives (e.g., variousprocessing aids, mold release agents). Precursor compositions for aplastic material may include un-crosslinked polymer components and avariety of other components, for example curing agents (e.g.,cross-linking agents), processing aids (e.g. viscosity modifiers),plasticizers and other additives.

Examples of some uncured thermoset resin compositions of a precursorcomposition may be or include: epoxy resins, phenolic resins, polyesterresins, unsaturated polyesters, polyimide resins, polyimine resins,polyurethane resins, vinyl esters, cyanate esters, bismaleimides,benzoxazines, phthalonitriles, polybutadiene, and combinations thereof.Some example themoset matrix materials include any cured compositionmade using such example precursor compositions. Some specific thermosetmatrix materials, or precursor compositions or components for suchprecursor compositions, include Recyclamine® (epoxy resin, ConoraTechnologies) and Recycloset™ (epoxy resin Adesso Advanced Materials).As noted, the composite may include a thermoset prepreg composite. Suchprepreg may be or include scrap and/or trim prepreg waste.

As noted, a matrix may be or include a thermoplastic composition. Someexample thermoplastic compositions include those based on or including:polyolefins (e.g., including polyethylene, polypropylene and/orpropylene-ethylene copolymers), polyethylene terephthalates (PET),polybutylene terephthalates (PBT), polycarbonates, acrylonitrilebutadiene styrenes (ABS), polyamides, polyetheretherketones (PEEK),polyetherketones (PEK), polyamide-imides, polyarylsulfones,polyetherimides (PEI), polyethersulfones, polyphenylene sulfides, liquidcrystal polymers, cyclic thermoplastic polyesters, and combinationsthereof.

As can be appreciated, in such composites, the matrix may hold orotherwise retain the reinforcing fibers in a certain arrangement ororientation. While the sized fiber product is provided in the absence ofsuch matrix, the surface properties of the sized reinforcing fibers mayprovide some degree of interaction between respective ones of thereinforcing fibers. However, this potential interaction is not intendedto define a matrix. Moreover, upon removal of the fiber sizing materialfrom the reinforcing fibers, the reinforcing fibers may move to adifferent orientation, possibly at least in part due to a change in therelative surface characteristics between fibers. This does not result inthe sized fiber product being provided in a matrix even if the degree towhich reinforcing fibers are mechanically stable relative to one anotheris decreased after processing to remove fiber sizing from thereinforcing fibers. That is, a matrix is intended to refer to a matrixincluding a plastic material or plastic composition described above suchthat sized fiber product including only reinforcing fibers and fibersizing material is not considered to define a matrix regardless of anyinteraction of the fibers or change in interaction of the fibers beforeor after processing to remove the fiber sizing material from the fibers.During the first treating, the dissolution of fiber sizing material maybe conducted to a degree to remove a majority or even most of the fibersizing material, so that after the first and second treating, the fibersmay have different interaction, orientation, or arrangement.

In an embodiment, the sized fiber product may be in a continuous formcomprising continuous reinforcing fibers. In addition, the first treatedsolid residue and the second treated solid residue each includes thecontinuous reinforcing fibers maintained in the continuous form.Continuous forms of a sized fiber product may include any product thatincludes continuous reinforcing fibers. Examples of contemplatedcontinuous forms include unidirectional sheet material, tow, and fabric.In this regard, the continuous form may include substantially onlyunidirectional fibers (e.g., unidirectional sheet or tow) or may includemultiaxial fibers having at least a portion of the fibers arranged suchthat the fibers extend in a continuous manner along a given axis of thematerial (e.g., non-woven or woven fabric). While the present disclosurecontemplates maintaining reinforcing fibers of the sized fiber productto be processed in the continuous form, it may be appreciated thatmaintaining the fibers in continuous form may include maintainingsubstantially all or even most of the fibers in continuous form. Forinstance, certain portions of the reinforcing fibers may be trimmed orotherwise disturbed in the process described herein. However, suchportions are preferably minimized and may comprise no more than 10% ofthe total continuous reinforcing fiber processed, no more than 5% of thetotal continuous reinforcing fiber processed, or no more than 1% of thetotal continuous reinforcing fiber processed. Additionally, continuousreinforcing fibers are intended to refer to reinforcing fibers that mayextend in a continuous form for a given length (e.g., relative to alength of the sized fiber product spooled about a source spool). Thegiven length of a continuous form, for example, as provided on a spool,that is provided as feed to processing, or that is subjected to solventprocessing (e.g., after end trimming) may be at least about 1 m, atleast about 5 m, at least about 10 m, at least about 25 m, at leastabout 50 m, or even at least about 100 m. It may be appreciated that thecontinuous reinforcing fibers may, but need not, extend along anentirety of a major length of the sized fiber product to be recycled orfrom which fibers are to be recovered.

By a continuous form it is meant a reinforcing fiber configuration(e.g., uniform or repeating pattern) extending over a significant lengthof a product form (e.g., initial product, intermediate processingproduct such as in a web, or final product). Examples of such continuousforms include unidirectional fiber forms (e.g., in composite tows) or,woven fiber forms (e.g., in reinforced fabric sheets) or nonwoven fiberform (e.g. in reinforced fabric sheets) that extend in a continuousmanner over a significant length for example over any of the lengthsidentified above. Such products including a continuous form ofreinforcing fibers may be referred to as continuous products orcontinuous-form products. Reinforcing fibers in such a continuous formmay be referred to herein as continuous reinforcing fibers orcontinuous-form reinforcing fibers. As may be appreciated, a continuousform including the reinforcing fibers may or may not be longer than thelengths of individual reinforcing fibers contained in the continuousform (e.g., fibers spun together into a longer thread-like form). Inpreferred embodiments, the continuous form of the reinforcing fibers issuch that it has sufficient structural integrity to be spooled andunspooled without destroying the continuous form even in the absence ofa matrix or when the matrix of an original fiber-reinforced compositehas been completely removed. As may be appreciated, when reference ismade to maintaining a continuous form during processing it is not meantthat there may be no change, however small, to the reinforcing fiberconfiguration. For example, as described above, after the fiber sizingis removed from a sized fiber product, the geometry of the reinforcingfibers may move or reorient to some degree within the continuous form,as the reinforcing fibers may reorient in the absence of fiber sizing onthe surface of the reinforcing fibers. For example, a continuous formgenerally may expand or contract by some degree during processing, forexample as a result of a magnitude of tension applied duringspool-to-spool processing of the continuous form in the absence of fibersizing material.

Such continuous products may be provided in spools of material or thelike. Spooled material in a form as may be available for recyclingprocessing may be difficult to process using the solvent-basedapproached described herein as the physical arrangement of the spooledcontinuous material may provide difficulty in effective solventtreatment to the entirety of the depth of the spooled material with asolvent. As such, approaches described herein may include respoolingcontinuous fibers onto a different spool in a manner more advantageousfor effective solvent treatment of the fibers prior to exposing thecontinuous fibers to the solvent-based approached described herein. Suchrespooling may include transferring the fibers to a spooled form havingcharacteristics advantageously enhanced for effective solvent-basedprocessing. This may include selection of spool material and/or designscompatible with or optimized for more uniformly exposing the fibers tothe solvent. In some embodiments, such a selectively respooled form mayadvantageously be treated with solvent as a unit with the continuousform of reinforcing fibers retained on the spool during solventcontacting.

The present disclosure also includes embodiments in which thesolvent-based techniques described herein may be applied to fibers in acontinuous form as the fibers in the continuous form are transferredbetween a first or source spool and a second spool, such as adestination or intermediate spool. Such processing may be carried outsuch that a single solvent treatment is carried out as fibers are passedfrom spool to spool with multiple phases of spooling to accomplishrespective ones of the treating steps of the solvent-based processing.Alternatively, multiple solvent treatments may be carried out in asingle instance of passing fibers from a first spool to a second spool.

These processes may include processing in a web including the continuousform of fibers that is separated from and extends between spools. Aswill be described in greater detail below, reference to a web isintended to refer only to a portion of material separated from a spool(e.g., the portion of fibers suspended between a first spool and secondspool) during spool-to-spool processing and is not intended to denoteany particular form or composition of the material within such amaterial portion. That is, a web may include unidirectional or uniaxialfiber orientations or may have, but need not have, multiaxial fiberorientations. In this regard, while the web may include reinforcingfibers that extend between spools, the composition of the web may bealtered by processing as it is transferred between the spools (e.g.,through removal and/or addition of matrix and/or fiber sizing duringprocessing).

Processing described herein carried out on the web may have advantagesrelative to effective contracting of the web material with solventduring solvent treatment of the present disclosure. That is, whilespooled material may be difficult to uniformly adequately wet with asolvent in a given treating, treating the material in a web betweenspools may facilitate more uniform treatment of the material with asolvent, thus allowing for processing of very large quantities of sizedfiber product provided in large spools (e.g., with layer counts of 100or more layers, 200 or more layers, 500 or more layers, or even 1000 ormore layers). In any regard, the processing described herein maymaintain reinforcing fibers in a continuous form during the recycling tominimize severing, tangling, or fraying of the fibers.

In an embodiment, the sized fiber product may be respooled to adestination spool adapted for performing the first treating and/orsecond treating on the sized fiber product on the destination spool. Inthis regard, the method may include transferring the sized fiber productin the continuous form from a source spool to the destination spool. Thetransferring may occur prior to the first treating. In this regard, thespooled material about the destination spool may undergo thesolvent-based processing, which may involve solvent treating thecomposite on the spool as a unit, rather than as a web between spools.

Accordingly, the source spool may be comprised of a first material ofconstruction and the destination spool may be comprised of a secondmaterial of construction. The first material may be different than thesecond material. Specifically, the second material may be compatiblewith the first solvent and the second solvent. As an example, the secondmaterial may be stainless steel or the like.

In addition, the destination spool may be configured to assist ineffectively treating the material with the fibers spooled thereabout.For example, the destination spool comprises a perforated cylindricalbody about which the continuous reinforcing fibers are wound. Inaddition, a spool dimension of the destination spool may be differentthan the corresponding spool dimension of the source spool. The spooldimension comprises at least one of a spool length or a spool diameter.In an embodiment, the destination spool diameter may be smaller than thesource spool diameter. Additionally or alternatively, the spool lengthof the destination spool may be larger than the spool length of thesource spool. The spool dimension for the destination spool may beselected to improve wetting of the fibers and/or to optimize the size ofa vessel required to house the destination spool. Advantageously,increasing spool length may provide fewer layers of wound material topenetrate with a solvent and/or a smaller diameter spool that may beprocessed in a smaller-diameter pressure vessel.

In addition to the physical properties of the spool, the manner in whichthe fibers are wound about the destination spool may be configured toassist in fiber wetting. As such, the continuous reinforcing fibers maybe wound on the destination spool in a manner different than the sourcespool. In an embodiment, the continuous reinforcing fibers may be woundon the destination spool in a wind geometry different than the sourcespool. The wind geometry may include the angle relative to the spool atwhich the fibers are wound about the spool, fiber spacing relative tothe spool, the number of fiber layers provided on the spool, or thelike.

It may be appreciated that treatability of fibers on the destinationspool may at least in part be based on the number of layers provided onthe destination spool. As such, the destination spool dimension and windgeometry may be selected to maximize the amount of fiber accepted on thedestination spool while minimizing the number of layers of fiber on thedestination spool. In any regard, a maximum wind thickness for thedestination spool may be established. In various embodiments, thecontinuous reinforcing fibers are wound onto the destination spool at awind thickness of no more than 100 layers of the sized fiber product, nomore than 50 layers of the sized fiber product, no more than 25 layersof the sized fiber product, or even no more than 10 layers of the sizedfiber product.

In another embodiment, the continuous reinforcing fibers may be treatedwith solvent treatments of the solvent-based processing as the fibersare transferred between a first spool and a second spool. Accordingly,the method may include transferring a web comprising the continuousreinforcing fibers in the continuous form between a source spool and anintermediate spool. The first treating comprises contacting the web withthe first solvent to prepare the first treated solid residue comprisingthe continuous reinforcing fibers. In turn, the method may includespooling the first treated solid residue on the intermediate spool withthe reinforcing fibers maintained in the continuous form.

In an application, at least a portion of the web is passed through afirst bath of the first solvent during the first treating. Additionally,in some contexts, at least a portion of at least one of the source spoolor the intermediate spool may be immersed in the first bath of the firstsolvent during the first treating. Further still, the source spool, theintermediate spool, and the web may be immersed in the first bath of thefirst solvent during the first treating. As may be appreciated, whilecontacting the web with the first solvent may allow for significantinteraction between the solvent and the sizing material contained in theweb, contact with the source spool or destination spool may alsofacilitate contact between at least some of the external-most layers ofthe spool. As such, disposing one or more of the spools in the solventbath may assist in facilitating contact of the sized fiber product witha solvent. In another approach, the web may contact a roller to guidethe web on a path through the first bath of the first solvent. In thisregard, the spools may be maintained outside the first solvent bath andonly the web may be contacted with the solvent.

The method may also include transferring the web of the continuousreinforcing fibers between the intermediate spool and a destinationspool. The second treating may include contacting the web with thesecond solvent to prepare the second treated solid residue comprisingthe reinforcing fibers and spooling the second treated solid residue onthe destination spool in the continuous form. In this regard, like withrespect to the processing of the web in the first treating, the secondtreating may include passing at least a portion of the web through asecond bath of the second solvent during the second treating. In anapplication, at a portion of at least one of the intermediate spool orthe destination spool may be immersed in the second bath of the secondsolvent during the second treating. In another application, theintermediate spool, the destination spool, and the web are immersed inthe second bath of the second solvent during the second treating. In anapproach, the web may contact a roller to guide the web along a paththrough the second bath of the second solvent.

In an application, the source spool and the destination spool maycomprise a common spool. That is, the web may be transferred between thesource spool and the intermediate spool and the first treating may becarried out with respect to the continuous reinforcing fibers duringthis transferring. Subsequently, the web may be transferred between theintermediate spool and the source spool (e.g., returned to the sourcespool as the destination spool) and the second treating may be carriedout with respect to the continuous reinforcing fibers during thetransferring between the intermediate spool and the source spool as thedestination spool.

In an application, a solvent treatment may be carried out using a sprayof solvent that contacts the web of reinforcing fibers. As will bediscussed in greater detail below, use of such a spray of solvent mayprovide efficiencies in relation to solvent usage and/or improvedmechanical actions of the spray relative to the web. In any regard, atleast a portion of the web may be contacted with a continuous spray ofthe first solvent during the first transferring. Similarly, at least aportion of the web may be contacted with a continuous spray of thesecond solvent during the second transferring.

While the foregoing contemplated use of an intermediate spool aboutwhich the first treated solid residue is wound prior to undergoing thesecond treating, in at least some embodiments, both the first treatingand second treating may be performed on a web extending between a firstspool and a second spool. In this regard, both the first treating andthe second treating may occur in relation to a single instance in whichthe continuous reinforcing fibers are transferred from the first spoolto the second spool. As such, the method may include transferring a webcomprising the continuous reinforcing fibers between a source spool anda destination spool. The first treating may include contacting the webcomprising the fiber-reinforced composite from the source spool with thefirst solvent to prepare the first treated solid residue comprising thecontinuous reinforcing fibers. The second treating may include removingthe residual portion of the first solvent from the first treated solidresidue from the web following the first treating and prior todestination spool (e.g., using a heating element and/or second solvent).

In an embodiment, a first bath of the first solvent and a second bath ofthe second solvent may be provided. As such, the web be guided by aplurality of rollers along a path through the first bath of the firstsolvent and through the second bath of the second solvent between thesource spool and the destination spool. As may be appreciated, a portionof the web (e.g., the portion between the source spool and the firstbath) may comprise sized fiber product. Additionally, a portion of theweb may comprise first treated solid residue (e.g., the portion betweenthe first bath and the second bath). Further still, a portion of the webmay comprise second treated solid residue (e.g., the portion of the webbetween the second bath and the destination spool). In addition, in thecontext in which the web is exposed to both the first treating andsecond treating, sprayers may be used for solvent application. In thisregard, the first treating may include contacting the web with acontinuous spray of the first solvent during the first transferring.Additionally or alternatively, the second treating may includecontacting the web with a continuous spray of the second solvent duringthe second transferring.

Regardless of the manner in which the first treating and/or secondtreating occurs, as described above, the continuous reinforcing fibersmay be configured as tow, a unidirectional sheet, a nonwoven fabric, ora woven fabric. Additionally, it has been found that it may beadvantageous to maintain the web, and the continuous reinforcing fibers,in tension during processing to help reduce fraying and tangling of thefibers. Accordingly, the method may include maintaining a tensile forceon the web, and on the continuous reinforcing fibers in the continuousform, during the transferring. The tensile force may be at least about20 N, and in some embodiments, may be less than 1,000 N. The tensileforce maintained on the web may be, at least in part, based on the size(e.g., including sheet width, tow size, or the like) and/or form of thereinforcing fibers (e.g., sheet, tow, etc.). While the continuousreinforcing fibers may be any appropriate material as described above,in preferred embodiments, the continuous reinforcing fibers comprisecarbon fibers.

Furthermore, the processing of the continuous reinforcing fibers mayinclude additional processing beyond the solvent-based processing toremove the sizing material from the reinforcing fibers. For instance,the continuous reinforcing fibers may be further processed whilemaintaining the reinforcing fibers in the continuous form. This mayinclude application of sizing material to resize the continuousreinforcing fibers. Additionally, a resin material may be applied to thereinforcing fibers after processing to remove the original fiber sizingmaterial and after application of new fiber sizing material.Accordingly, the method may include, after the second treating,contacting at least a portion of the second treated solid residue withat least one of a sizing material or a resin material (e.g., toestablish a matrix relative to the continuous reinforcing fibers). Thesecond treated solid residue may be maintained in the continuous formduring the contacting of the second treated solid residue with thesizing material and/or the resin material. Specifically, the contactingthe second treated solid residue with the sizing material and/or resinmaterial may occur prior to winding the continuous reinforcing fibersonto the destination spool.

Furthermore, it may be understood that the processing described in thepresent disclosure may, at least in part, be performed in one or moreprocess vessels that may contain one or more of the spools, web, and/orsolvents. In an embodiment, the first treating and the second treatingmay occur in a single process vessel. Alternatively, the first treatingand second treating may occur in different process vessels. In anyregard, it may be appreciated that the normally-gaseous second solventmay be maintained in a liquid or supercritical fluid form. In thisregard, the process vessel in which the second treating using the secondsolvent occurs may be maintained at an elevated pressure (e.g., of atleast 2 MPa). This may be regardless of whether the second treatingusing the second solvent occurs in the same or a different processvessel as the first treating. Accordingly, the process vessel in whichthe first treating occurs may be at the elevated pressure or may bemaintained at a pressure in a range of from 0.1 MPa to 1 MPa during thefirst treating.

In a particular embodiment, the single process vessel used in the firsttreating and second treating may include both a first bath of the firstsolvent and a second bath of the second solvent. In this regard, thefirst solvent may be isolated from the second solvent in the singleprocess vessel. In an alternative embodiment, the first solvent may beintroduced into the single vessel for the first treating during a firsttime period and the second solvent may be introduced into the singlevessel for the second treating during a second time period. The firsttime period and the second time period may be different (e.g., includedistinct and non-overlapping time periods).

The method may include additional processing steps, for example, beforethe first treating (e.g., to prepare a feed of the sized fiber productto the first treating), between the first treating and the secondtreating (e.g., liquid-solid separation or thermal drying to vaporize aportion of residual first solvent) or after the second treating (e.g., athird treating). Likewise, the first treating may include processing inaddition to the dissolving and the second treating may includeprocessing in addition to the contacting. The method may includemultiple first treating, second treating and/or third treating steps,which may be consecutive or separated by one or more interveningprocessing steps.

The method may also include ancillary operations, for example, forrecovering, treating and/or recycling one or more of the following:

-   -   first solvent used to dissolve sizing material during the first        treating,    -   sizing material dissolved into the first solvent during the        first treating, and    -   normally-gaseous material used in the second treating.

For example, the method may include recovering rich first solvent fromthe first treating, with the rich first solvent being rich in dissolvedmaterial of the sizing, distilling the rich first solvent to vaporizefirst solvent, and preferably accompanied by precipitation of solids ofthe material of the sizing. Distilled vapor of the first solvent may becondensed and recycled as feed to the first treating. Precipitatedsolids of sizing material may be recovered (e.g., by filtration ofdistillation bottoms) and may be recycled.

As another example, the method may include recovering some or all of thenormally-gaseous material from the second treating, recovering anydissolved material from the normally-gaseous material following thesecond treating (e.g., through pressure reduction to reduce solubilityand/or distillation to convert the normally-gaseous material to a gasform at elevated pressure), or separating from the normally-gaseousmaterial any suspended fine solids that may be mixed with thenormally-gaseous material as recovered from the second treating.Cleansed normally-gaseous material may then be compressed and/orsubjected to temperature adjustment as needed and recycled as feed foradditional use in the second treating operation. The normally-gaseoussubstance of the third treating may also be recovered following thesecond converting and likewise processed and recycled.

Other aspects, feature refinements and additional features are disclosedin and/or will be apparent from the drawings in conjunction with thesummary provided above and the description that follows and from theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a generalized process block diagram illustrating an example ofprocessing of an aspect of this disclosure.

FIG. 2 is a generalized process block diagram illustrating anotherexample of processing of an aspect of this disclosure.

FIG. 3 is a generalized process block diagram illustrating anotherexample of processing of an aspect of this disclosure.

FIG. 4 is a generalized process block diagram illustrating anotherexample of processing of an aspect of this disclosure.

FIGS. 5-11 are SEM images of recovered carbon fibers from Examples 1-11,respectively, presented below.

FIG. 12 is a schematic view of an embodiment of a source spool and adestination spool for transfer of continuous reinforcing fibers betweenthe source spool and the destination spool.

FIG. 13 is a perspective view of an embodiment of a destination spoolhaving continuous fibers wound about the destination spool.

FIG. 14 is a partial schematic view of an embodiment of a processvessel, shown partially translucent for clarity of explanation, that maybe used in treating continuous reinforcing fibers.

FIG. 15 is a schematic view of an embodiment for continuous processingof a web comprising reinforcing fibers transferred between a sourcespool and an intermediate spool in which the source spool, destinationspool, and the web are immersed in a first bath of a first solvent.

FIG. 16 is a schematic view of an embodiment for continuous processingof a web comprising reinforcing fibers transferred between anintermediate spool and a destination spool in which the source spool,destination spool, and the web are immersed in a first bath of a firstsolvent.

FIG. 17 is a schematic view of an embodiment for continuous processingof a web comprising reinforcing fibers transferred between a sourcespool and an intermediate spool in which the web travels along a paththrough a first bath of a first solvent.

FIG. 18 is a schematic view of an embodiment for continuous processingof a web comprising reinforcing fibers transferred between anintermediate spool and a destination spool in which the web travelsalong a path through a second bath of a second solvent.

FIG. 19 is a schematic view of an embodiment for continuous processingof a web comprising reinforcing fibers transferred between a sourcespool and an intermediate spool in which the web is contacted with acontinuous spray of a first solvent.

FIG. 20 is a schematic view of an embodiment for continuous processingof a web comprising reinforcing fibers transferred between anintermediate spool and a destination spool in which the web is contactedwith a continuous spray of a second solvent.

FIG. 21 is a schematic view of an embodiment for continuous processingof a web comprising reinforcing fibers transferred between a sourcespool and a destination spool in which the web is in contact with afirst bath of a first solvent and a second bath of a second solvent.

FIG. 22 is a schematic view of an embodiment for continuous processingof a web comprising reinforcing fibers transferred between a sourcespool and a destination spool in which the web is in contact with afirst bath of a first solvent and is passed in relation to a heatingelement for removal of the first solvent from the web.

FIG. 23 is a schematic view of an embodiment for continuous processingof a web comprising reinforcing fibers transferred between a sourcespool and a destination spool in which the web is contacted with acontinuous spray of a first solvent and a continuous spray of a secondsolvent.

FIG. 24 is a schematic view of an embodiment for continuous processingof a web comprising reinforcing fibers transferred between a sourcespool and a destination spool in which the web is in contact with afirst bath comprising a first solvent, a second bath comprising a secondsolvent, and a third bath.

DETAILED DESCRIPTION

FIG. 1 show a generalized process block diagram illustrating someexample implementations of a method for processing a fiber-reinforcedcomposite for recovery of reinforcing fibers. As described above, whilethe following description generally describes processing of afiber-reinforced composite to remove a matrix and/or fiber sizingmaterial from reinforcing fibers, the techniques may equally be appliedto a sized fiber product in the absence of a matrix to remove fibersizing material from the reinforcing fibers. As such, references belowto a fiber-reinforced composite are equally applicable to a sized fiberproduct in the absence of a matrix and reference to a matrix materialare equally applicable to fiber sizing material.

In the generalized processing shown in FIG. 1, a feed of afiber-reinforced composite 102 is subjected to first treating 104 duringwhich the composite 102 is contacted with a first solvent 106 underconditions to dissolve into the first solvent 106 at least a majority byweight of the matrix of the composite 102. Rich first solvent 108including dissolved material of the matrix from the first treating 104may be recovered and processed as desired, for example to recovermaterial of the matrix and prepare lean first solvent for recycling backto the first treating 104 as part of the first solvent 106 feed. Aresult of the first treating is first treated solid residue 110, atleast a portion of which is subjected to second treating 112. The firsttreated solid residue 110 includes the reinforcing fibers freed from thematrix of the composite 102, but still in the presence of residual firstsolvent. During the second treating 112, at least a portion of the firsttreated solid residue 110, and preferably all or essentially all of thefirst treated solid residue 110, is contacted with a second solvent 114.Rich second solvent 116 containing dissolved first solvent 106 that isremoved from the presence of the first treated solid residue 110 duringthe second treating 112 may be recovered from the second treating 112and processed as desired. The second solvent 114 may also dissolve someof and/or carry away some particulates of residual material of thematrix that may remain in the first treated solid residue 110 followingthe first treating 104. A result of the second treating 112 is a secondtreated solid residue 118 that has been cleansed of at least a portion,and preferably essentially all, residual first solvent 106 associatedwith the first treated solid residue 110 following the first treating,and preferably the second treated solid residue 118 also has beencleansed of at least a portion of residual material of the matrix thatmay remain in the first treated solid residue 110 following the firsttreating 104. Preferably, the second treated solid residue 118 is madeup almost entirely of reinforcing fibers, although such reinforcingfibers may still be associated with a small residual amount of matrixmaterial and and/or some fiber sizing material in the form of a thincoating on the reinforcing fibers when the reinforcing fibers are of atype that originally were protected by a coating of sizing materialprior to manufacture of the composite 102.

With continued reference to FIG. 1, the first solvent 106 is anormally-liquid material (e.g., methylene chloride) with a significantsolvating capacity for dissolving and carrying away material of thematrix from the composite 102, and the first solvent is contacted withthe composite 102 under conditions of temperature and pressure at whichthe first solvent 106 is in a liquid form. In contrast, the secondsolvent 114 is a normally-gaseous material (e.g., carbon dioxide) thatis contacted with the first treated solid residue 110 under conditionsof temperature and pressure at which the second solvent 114 is in theform of a liquid or supercritical fluid. In some implementations, thesecond treated solid residue 118 may remain in a mixture with some ofthe second solvent 114, which may be beneficial for some furtheroptional processing of the second treated solid residue, for exampleprocessing of a type as illustrated in FIG. 2 or 3, discussed below.

Reference is now made to FIG. 2 which shows a generalized process blockdiagram illustrating some example implementations of a method forprocessing a crude product containing reinforcing fibers recovered fromprior processing of a composite including the reinforcing fibers. Asshown in FIG. 2, a feed of such a crude product 120 and a feed of afluid form 124 of a normally-gaseous substance are subjected to a firstconverting step 122 in which, in the presence of the crude product, thenormally-gaseous substance is converted from the fluid form 124 (i.e.,liquid, gas or supercritical fluid) to a solid form in contact with thecrude product. The feed of the crude product 120 preferably is made upmostly of freed reinforcing fibers, but may typically include someresidual matrix material and/or fiber sizing material. During the firstconverting step 122, the temperature of the normally-gaseous substanceis reduced, which may accompany a change in pressure of thenormally-gaseous substance. In an example implementation, the firstconverting step may involve gas expansion cooling associated withreducing the pressure of the normally-gaseous substance from ahigh-pressure state to a low-pressure state. For example, during thefirst converting step 122 a mixture of the crude product and thenormally-gaseous substance may be initially contained in a pressurevessel with the normally-gaseous substance under very high pressure in aform of a high pressure gas, liquid or supercritical fluid. The pressurevessel may then be depressurized through venting of a portion, or evenmost, of the normally-gaseous substance as a vent stream 125 from thepressure vessel at a sufficiently rapid rate to reduce the temperaturewithin the pressure vessel to a temperature at which at least a portionof the normally-gaseous substance initially in the pressure vessel iscooled sufficiently to convert to a solid form in contact with the crudeproduct in the depressurized pressure vessel. Such a vented portion ofthe normally-gaseous substance is illustrated in FIG. 2 by a vent stream125 shown as a dashed line.

A result of the first converting 122 is a mixture 126 including thecrude product and the solid form of the normally-gaseous substance.Preferably, such solid form is present in void spaces in and aroundresidual matrix material and fiber sizing material, and with a portionof the solid form impregnating the residual matrix material and fibersizing material. Such impregnation may result from penetration, such asby diffusion, of the fluid form of the normally-gaseous substance intosuch residual matrix material and fiber sizing material, with some ofsuch penetrating fluid then converting to the solid form within thematrix material and fiber sizing material as the pressure andtemperature are reduced.

After the first converting step 122, the mixture 126 including the crudeproduct and the solid form of the normally-gaseous substance issubjected to a second converting step 128, during which thenormally-gaseous substance of the mixture 126 is converted from thesolid form into a gaseous form, and preferably at a very rapid rate. Inthat regard, the second converting step 128 may include rapidsublimation of the solid form to the gaseous form. During the secondconverting step 128 as illustrated in FIG. 2, heat is supplied torapidly convert the solid form of the normally-gaseous substance to agaseous form by contacting the mixture 126 with a heat transfer fluid130. This may be accomplished in any way to quickly warm the mixture126. In the example illustrated in FIG. 2 the heat is supplied bycontacting the mixture 126 with the heat transfer fluid 130 that is at ahigher temperature than the temperature of the mixture 126. As shown inFIG. 2, a feed of a heat transfer fluid 130 is fed to the secondconverting to contact and warm the mixture 126 and cause conversion ofthe solid form of the normally-gaseous substance to the gaseous form.Such a feed of heat transfer fluid 130 may be, for example, in the formof a liquid (e.g., heated water, heated oil), a gas (e.g., steam, carbondioxide, nitrogen), or multiphase (e.g., saturated steam/water mix). Inthe example shown in FIG. 2, effluent 132 of the normally-gaseoussubstance in gaseous form and effluent 134 of the heat transfer fluidare removed from the second converting 128, and may be recoveredseparately or in a mixture from the second converting 128. A cleanedproduct 136 is recovered from the second converting 128. The cleanedproduct 136 includes the reinforcing fibers cleaned of at least aportion of residual material of the matrix and/or sizing material thatwere present in the feed of the crude product 120. Particles ofdislodged matrix material and/or sizing material may be recovered witheffluent 132 of the normally-gaseous substance and/or the effluent 134of the heat transfer fluid. The feed of the crude product 120 to theprocessing of FIG. 2 may result from any prior processing. In someimplementations, the crude product 120 that is fed to the processing ofFIG. 2 may be provided by first treated solid residue 110 or secondtreated solid residue 118 prepared in the processing shown in FIG. 1.

FIG. 3 is a generalized process block diagram illustrating some exampleimplementations of processing including the first treating 104 andsecond treating 112 of FIG. 1 combined with third treating 140 includingthe first converting 122 and the second converting 128 of FIG. 2, inwhich second treated solid residue 118 from the second treating 112 isused as the feed of crude product 120 for the first converting 122. Thesame reference numerals are used in FIG. 3 to refer to like featuresshown in and described in relation to FIGS. 1 and 2, except as statedotherwise. In the processing of FIG. 3, a portion of the second solvent114 from the second treating 112 is used as the feed of the fluid form124 of a normally-gaseous substance to the first converting 122. Suchfeed of the fluid form 124 of a normally-gaseous substance may be, forexample, relatively clean fluid following flushing out most of theresidual first solvent 106 from the first treated solid residue 110during the second treating 112, which is recovered in the rich secondsolvent 116. In the example processing of FIG. 3, the first treating104, second treating 112, first converting 122 and the second converting128 may be as described previously with reference to FIGS. 1 and 2.

In the processing shown in FIGS. 1 and 3, the first treating 104 andsecond treating 112 may be performed in a single process vessel or maybe performed in separate process vessels. The first treating 104 may beperformed in a liquid containment vessel that need not be a pressurevessel, whereas the second treating 112 will typically be performed in apressure vessel. The first treating 104 and second treating 112 may beperformed in a batch, continuous or semi-continuous operation. In theprocessing of FIGS. 2 and 3, the first converting 122 and the secondconverting 128 will each typically be performed in a pressure vessel,and which may be in a single pressure vessel or in separate pressurevessels. The first converting 122 and the second converting 128 may beperformed in a batch, continuous or semi-continuous operation. Forcontinuous or semi-continuous processing, the first converting 122 andsecond converting 128 will typically be performed in separate pressurevessels. For batch processing, the first converting 122 and secondconverting 128 may conveniently be performed in a single pressurevessel.

FIG. 4 is a generalized process block diagram showing the same exampleprocessing as shown in FIG. 3, but also illustrating examples of someancillary processing to treat rich first solvent 108 to recover matrixmaterial, to recycle lean first solvent for reuse and to regeneratesecond solvent. The same reference numerals are used in FIG. 4 toidentify like features as are shown and described in relation to FIGS.1-3. In the example processing shown in FIG. 4, the rich first solvent108 is subjected to distillation 142 to remove dissolved matrix materialand to regenerate clean first solvent for reuse. During the distillation142, overhead including first solvent vapor 144 is collected andsubjected to a condensing operation 146 to condense first solvent vaporand prepare regenerated lean first solvent 148 in liquid form that maybe recycled for use to prepare additional feed of the first solvent 106to the first treating 104. FIG. 4 also shows an optional bleed 150 toremove first solvent as needed. Optionally, some condensed first solvent152 may be returned to the distillation 142 as reflux. Distillationbottoms 154 containing liquid first solvent and precipitated material ofthe matrix are subjected to a filtration operation 156. A retentateportion 158 including precipitated solids of the matrix material isrecovered and a filtrate portion 160 is subjected to a re-boil 162 tovaporize first solvent for return to the distillation 142.

The effluent 132 of the normally-gaseous substance (second solvent) andthe effluent 134 of the heat transfer fluid from the second converting128 are processed in a separation operation 164. The effluents 132 and134 may be partly or entirely in a combined stream. In the separationoperation 164, second solvent may be flashed from the heat transferfluid to prepare recovered normally-gaseous substance 166 and solids(e.g., of matrix material and/or fiber sizing) may be filtered from theheat transfer fluid to prepare recovered heat transfer fluid 168 andrecovered solids 170. The vent 125 of normally-gaseous substance (secondsolvent) from the first converting 122, the recovered normally-gaseoussubstance 166 and the rich second solvent 116 may be processed through asecond solvent regeneration operation 172. A bleed 186 of second solventmay optionally remove second solvent from the system as needed. In thesecond solvent regeneration operation 172, first solvent 106 dissolvedin the rich second solvent 116 may be recovered as a recovered firstsolvent 174, such as by distillation of the rich second solvent 116 toconvert the rich second solvent 116 to a gas form and to precipitatefirst solvent. During the second solvent regeneration operation 172,overhead including second solvent vapor 182 is collected and subjectedto a condensing operation 180 to condense second solvent vapor andprepare regenerated lean second solvent 176 in liquid form that may berecycled for use to prepare additional feed of the second solvent 114 tothe second treating 112. FIG. 4 also shows an optional bleed 178 toremove second solvent as needed. Optionally, some condensed secondsolvent 184 may be returned to the second solvent regeneration 172 asreflux. The recovered first solvent 174 may be further processed in thedistillation 142.

The foregoing discussion describes embodiments for recovery ofreinforcing fibers from a fiber-reinforced composite without regard tothe form in which the fiber-reinforced composite or the reinforcingfibers are provided. However, as recognized above, certainfiber-reinforced composites that are to be recycled for recovery and/orrecycling of the reinforcing fibers may be provided in a continuousform. Examples of such continuous forms include, but are not limited to,continuous tow, unidirectional sheets, non-woven fabric, woven fabric orany other form that may be provided with at least a portion of thereinforcing fibers in a continuous and/or specific arrangement. Bycontinuous reinforcing fibers, it is meant that the reinforcing fibersare arranged to be continuous relative to a given dimension of theproduct. The continuous fibers may have a minimum length of at leastabout 1 m, at least about 5 m, at least about 10 m, at least about 25 m,at least about 50 m, or even at least about 100 m or more. While thecontinuous fibers may correspond in length with an overallfiber-reinforced composite to be recycled, the continuous fibers may beof a length longer or shorter than the overall fiber-reinforcedcomposite length.

Such continuous forms of fiber-reinforced composites may include atleast a portion of the reinforcing fibers of the fiber-reinforcedcomposites as continuous reinforcing fibers. Moreover, continuousreinforcing fibers in a continuous form may also refer to the particulararrangement of the fibers. For example, fibers may be provided in aunitary sheet in which the reinforcing fibers are both continuous andarranged in a relatively uniform arrangement of fibers along a width ofthe continuous form transverse to the length of the continuous fibers.Furthermore, fibers provided as tow may have a particular bundlingformation including predetermined twists or the like that may bedesirably maintain during processing. In this regard, a continuous formof continuous reinforcing fibers may refer both to the continuity thefibers and or the arrangement of the fibers in the continuous form.Often times such continuous fiber-reinforced composite to be recycledincludes prepreg rolls of unitary sheet, prepreg rolls of carbon fibertow, or other continuous forms of prepreg material that have expired.

While such continuous reinforcing fibers could be cut and/or processedin a manner that does not maintain the continuous form of thereinforcing fibers, such processing may be disadvantageous as thecontinuous form of the reinforcing fibers may provide advantages inrelation to manufacturing processes, resulting manufactured productproperties, or the like. Moreover, once such reinforcing fibers areeither cut or disrupted (e.g., tangled, frayed, or the like), it may bedifficult or impossible to rearrange such fibers in a continuous form ina later processing step to retain the advantages of the originalcontinuous form of the fibers. Accordingly, the following discussionincludes embodiments that may allow for processing of continuousfiber-reinforced composite in accordance with the foregoing embodimentsfor processing to maintain the continuous reinforcing fibers of thecontinuous fiber-reinforced composite in continuous form. As theforegoing embodiments may include the processing described above, likenumerals will be utilized in the following to refer to the foregoingprocesses.

One embodiment that may be used to process continuous fiber-reinforcedcomposites may include a batch process in which the continuousfiber-reinforced composite is re-spooled from a source spool to adestination spool prior to undergoing processing. In turn, thedestination spool of fiber-reinforced composite may undergosolvent-based processing as described above. In this regard, thedestination spool and/or the manner in which the fiber-reinforcedcomposite is spooled onto the destination spool may aid in theeffectiveness of the solvent-based processing to be carried out on thespooled reinforcing fibers in the continuous form.

For instance, with further reference to FIG. 12, an embodiment 200 forprocessing continuous fiber-reinforced composite 102 may includetransferring the fiber-reinforced composite 102 from a source spool 202to a destination spool 204. The destination spool 204 and/or the mannerin which the continuous fiber-reinforced composite 102 is wound aboutthe destination spool 204 may assist in facilitating processing of thecontinuous fiber-reinforced composite 102 on the destination spool 204.For instance, the source spool 204 may be a spool about which thefiber-reinforced composite 102 was provided for use in a manufacturingprocess. In this regard, the source spool 202 may be a cellulose-basedmaterial such as a paper-based spool that may include reinforcedpaperboard, cardboard, or the like. Such spool material may not providedesirable mechanical properties when exposed to the solvent-basedprocessing described herein (e.g., the spool material may degrade or bedestroyed), which may include subjecting the spool to contact with orsubmersion in solvent.

Accordingly, the source spool 202 may comprise a first material ofconstruction and the destination spool 204 may comprise a secondmaterial of construction. The first material and the second material maydiffer. Specifically, the destination spool 204 may comprise a secondmaterial that may be suited for processing according to thesolvent-based processing described herein. For instance, the secondmaterial may be compatible with the first solvent and the secondsolvent. Moreover, the second material may provide increased mechanicalproperties that may withstand the physical requirements for maintainingthe physical integrity of the destination spool 204 during thesolvent-based processing described herein. As an example, the secondspool may be constructed from stainless steel or the like.

In addition, the destination spool 204 and/or the manner in which thecontinuous fiber-reinforced composite 102 is wound about the destinationspool 204 may also assist in effective contacting of the spooledmaterial with solvent as it is subjected to the solvent-based processingdescribed herein. As may be appreciated, the fiber-reinforced composite102 on the source spool 202 may be provided for use in a manufacturingprocess. The source spool 202 may include many layers of the continuousfiber-reinforced composite 102 such that penetration of a solvent to theinner layers of the spool may be difficult. Moreover, thefiber-reinforced composite 102 may also be spooled with additionalmaterial, such as backing material to prevent adhesion between layers orthe like. In turn, the transfer of the fiber-reinforced composite 102from the source spool 202 may remove any extraneous packaging material,reconfigure the spooled material about the designation spool 204,reduced the number of spooled layers, and/or dispose thefiber-reinforced composite 102 adjacent to features of the destinationspool 204 that promote effective contact of the spooled fiber-reinforcedcomposite 102 with a solvent.

In an embodiment depicted in FIG. 13, the destination spool 204 maycomprise a perforated cylindrical body about which the continuousreinforcing fibers of the continuous fiber-reinforced composite 102 arewound. This perforated cylindrical body may assist in effective contactbetween the continuous reinforcing fibers disposed about the destinationspool 204 and a solvent when exposed to the solvent-based processing.Specifically, the perforated destination spool 204 may allow for flow ofsolvent through the fibers from both external to the spooled materialand from within the spool to an exterior of the spooled material.

Additionally or alternatively, the manner in which the continuousreinforcing fibers are wound onto the destination spool may be in amanner different than that provided that the source spool 102. Forinstance, the fibers may be disposed on the source spool 202 in a givenwind geometry. This wind geometry may include various parametersincluding the angle relative to the spool at which the fibers are woundabout the spool, the spacing between adjacent fiber winds on the spool,or the like. In this regard, the wind geometry for the destination spool204 may be different than that of the source spool 202. For instance,the destination spool 204 may comprise a hoop wind in which the fibersare relatively densely wound about the destination spool 204. That is,the angle at which the fibers are wound about the destination spool 204may be nearly zero relative to a circumferential datum about thecylindrical body of the destination spool 204. In contrast, the sourcespool 202 may have a wind geometry with an angled wind in which theangle at which the fibers are wound relative to the circumferentialdatum is larger than that of a hoop wind to allow for improved strippingof the fibers from the spool.

In addition, to assist in promoting effective contact between the fiberson the destination spool 204 and a solvent, the continuous reinforcingfibers may be wound onto the destination spool 204 at a wind thicknesswith relatively few winding layers, for example no more than 100 layers.In this regard, the wind thickness refers to the number of layers ofcontinuous fiber wound about the destination spool 204. It may beappreciated that providing fibers at too great a wind thickness mayresult in the inability to sufficiently penetrate to fibers in layers ofthe spool 204 (e.g., adjacent to the spool body or in a region betweenthe exterior of the spool and an inner perforated wall of the spool) foreffective solvent treatment of all material on the spool.

Further still, the destination spool 204 may differ with respect to thesource spool 202 with regard to at least one spool dimension. The spooldimension may include a spool length or a spool diameter referring tothe length and diameter of the spool body, respectively. In this regard,a larger spool length may be provided for the destination spool 204 toallow for acceptance of a larger amount of continuous fiber withoutunduly increasing the layer count of the fiber. The spool diameter ofthe destination spool may be larger than or smaller than the spooldiameter of the source spool. In some implementations, the destinationspool 204 may have a smaller diameter than the source spool 204 topermit processing of the destination spool 204 in a processing vessel ofsmaller diameter.

With further reference to FIG. 14, the destination spool 204 may besubjected to any or all of the solvent-based processing as describedabove. In this regard, the destination spool 204 about which thefiber-based composite 102 is wound may be disposed within a processvessel 208. The destination spool 204 may undergo processing accordingto the foregoing description such that a first solvent 106 may beintroduced into the interior of the vessel 208 for contacting thefiber-reinforced composite 102 to perform a first treating 104 asdescribed above. As a result, a first treated solid residue 110 may bedisposed about the destination spool 204 at the conclusion of the firsttreating 104. Rich first solvent 108 may be removed from the vessel 208for processing as described above. Second solvent 114 may be introducedto the vessel 208 to perform second treating 112. Accordingly, at theconclusion of the second treating 112, a second treated solid residue118 may be disposed about the destination spool 204. Rich second solvent116 may also be recovered from the vessel 208 after the second treating112.

While FIG. 14 depicts a situation in which the first treating 104 andsecond treating 112 occurring in a single process vessel 208, it may beappreciated that the first treated solid residue 110 disposed about thedestination spool 204 may be removed from a first process vessel afterthe first treating 104 and disposed in a second process vessel in whichthe second treating 112 may occur. That is, the first treating 104 mayoccur in a first process vessel and second treating 112 may occur in asecond process vessel such that the destination spool 204 about whichthe continuous reinforcing fibers are disposed may be transferred fromthe first process vessel to a second process vessel between the firsttreating 104 and the second treating 112.

In addition, the second treated solid residue 118 disposed about thedestination spool 204 at the conclusion of the second treating 112 mayalso be exposed to third treating 140. This may occur in either theprocess vessel 208, a second process vessel in which the second treating112 occurred, or a third process vessel specific to the third treating140. In addition, the second treated solid residue 118 disposed aboutthe destination spool 204, with or without being exposed to the thirdtreating, may also be contacted with a sizing material and/or resinmaterial for further processing of the material. This may allow forresizing and/or generation of a finished fiber-reinforced compositematerial utilizing the second treated solid residue 118.

While FIGS. 12-14 describe a batch processing in which the destinationspool 204 about which the continuous reinforcing fibers are disposed isexposed to the various solvent-based processing, in other embodiments220 and 221 shown in FIGS. 15-16, the continuous reinforcing fibers maybe exposed to various solvent-based processing in a spool-to-spoolprocess. For instance, with further reference to FIG. 15, in theillustrated embodiment 220 a web 222 with continuous reinforcing fibersmay extend from a source spool 202 to an intermediate spool 206. As thefibers are transferred between the source spool 202 and the intermediatespool 206, the fibers may be separated from the source spool 202 todefine the web 222 extending between the source spool 202 and theintermediate spool 206. In turn, the web 222 may allow for improvedcontacting of the fibers with a solvent in the web 222 as the fibers aretransferred between the source spool 202 and the intermediate spool 206.

Accordingly, the web 222 is intended to refer only to material suspendedapart from a spool (e.g., the layer, portion, or strand of thecontinuous reinforcing fibers spanning between the source spool 202 andthe intermediate spool 206). That is, the web 222 is not intended referto any particular characteristics of the continuous reinforcing fibersuch as interlinking between the fibers, multiaxial properties of thefibers, or the like. As such, the web 222 may be a unidirectionalmaterial (e.g., unidirectional sheet, unidirectional tow, etc.) thatneed not, but could in at least some embodiments, include multiaxialfiber within the web 222. In short, web 222 simply refers to the portionof the material being processed with the continuous fibers extendingbetween the two given spools that is provided apart from any otherspooled material.

As shown in FIG. 15, the first solvent 106 may be introduced into aprocess vessel 224 to provide a first solvent bath 228 of the firstsolvent 106. In turn, the source spool 202, web 222, and intermediatespool 206 may all be submerged in the first bath 228 to contact the web222, the source spool 202, and the intermediate spool 206 to the firstsolvent 106. As may be appreciated, exposure of the web 222 to the firstsolvent bath 228 may improve contact between the reinforcing fibers inthe web 222 and the first solvent 106. In addition, while the firstsolvent 106 may not penetrate all layers wound about the source spool202, a certain number of exterior layers of the source spool 202 may beexposed to the first solvent 106 disposed in the first solvent bath 228.The web 222 may provide good contact between the reinforcing fibers andthe first solvent 106 to promote effective treatment for preparing thefirst treated solid residue 110 by effectively and uniformly dissolvingthe matrix of the composite 102. In turn, the first treated solidresidue 110 may be wound about the intermediate spool 206. The firsttreating 104 may comprise transferring the web 222 between the sourcespool 202 and the intermediate spool 206 such that at least the web 222is exposed to the first solvent 106 to prepare the first treated solidresidue 110.

Upon completion of the spooling of the fibers from the source spool 202to the intermediate spool 206, rich first solvent 108 may be removed andrecovered from the process vessel 224 as described above. With furtherreference to FIG. 16, in the illustrated embodiment 221 the secondsolvent 114 may be introduced into the process vessel 224 to create asecond solvent bath 230 of the second solvent 114. The second solventbath 230 may be introduced to the same process vessel utilized for thefirst treating 104, or the second solvent bath 230 may be introducedinto a different process vessel than that used for the first treating104, in which case the intermediate spool 206 may be transferred to thesecond process vessel prior to the second treating 212. In any regard,the fibers may be transferred between the intermediate spool 206 and adestination spool 204 such that a web 222 extending between theintermediate spool 206 and the destination spool 204 may be contacted bythe second solvent 114 as the web 222 passes through the second bath 230to prepare the second treated solid residue 118. The second solvent bath230 may also contact the exterior layers of both the intermediate spool206 and the destination spool 204 during the second treating 112. Richsecond solvent 116 may be recovered from the process vessel 224 uponcompletion of the second treating 112. In addition, the vessel 224 mayinclude a vapor space 226, which may be maintained at an elevatedpressure at least in connection with the second treating 112 asdescribed above.

In an embodiment, the destination spool 204 may be the same spool as thesource spool 202. In this regard, during the first treating 104, thefibers may be transferred between the source spool 202 and theintermediate spool 206 in the presence of the first solvent bath 228.Thereafter, the fibers may be transferred between the intermediate spool206 and the destination spool 204, which may be the same spool as thesource spool 202.

While the source spool 202, intermediate spool 206, and/or destinationspool 204 may be disposed partially or entirely within the first solventbath 228 and/or second solvent bath 230 for the respective firsttreating 104 and/or second treating 112, a portion of the web 222 alonemay contact the respective solvent bath as shown in FIGS. 17 and 18.FIGS. 17 and 18 depict alternative embodiments 232 and 233, each ofwhich utilizes a roller 234 to contact and guide the web 222 into eitherthe first solvent bath 228 or the second solvent bath 230 for therespective first treating 104 and second treating 112. In this regard,the spools between which the fibers are transferred may be providedwithin the vapor space 226 of the vessel 226 to isolate the spools fromthe solvent baths. As such, the first treating 104 and/or secondtreating 112 may occur only with respect to the portion of the web 222that follows the path through the respective solvent bath as shown inFIGS. 17 and 18. The roller 234 may also apply a desired tension to theweb 222.

With further reference to FIGS. 19 and 20, other embodiments 236 and 237are depicted in which a web 222 extending between spools may be exposedto respective solvents of the first treating 104 and second treating 112by a continuous spray 238 of the respective solvent. That is, the web222 may be sprayed by a sprayer 238 with a spray of the first solvent106 when being transferred between the source spool 202 and theintermediate spool 206 as shown for the embodiment 236 in FIG. 19. Inturn, rich first solvent 108 may be recovered from the vessel 224. Asshown for the embodiment 237 in FIG. 20, upon transferring the web 222between the intermediate spool 206 and the destination spool 204, thesecond solvent 114 may be sprayed on the web 222 by the sprayer 238 tocontact the web 222. As may be appreciated, the sprayer 238 may providesufficient flow to effectively contact the web 222 for sufficientsolvent contact for either the first treating 104 or the second treating112.

In this regard, rather than contacting the web 222 with a solvent bathby guiding the web 222 into the solvent bath or submersion of the weband/or spools into a solvent bath, the web 222 may be contacted by therespective solvent for the first treating 104 or second treating 112 bythe sprayer 238. It may be appreciated that utilization of the sprayer238 may allow for a reduced volume of solvent as compared to the solventbaths. This may be particularly useful for larger formats of continuousfiber such as uni-directional sheets or the like. Furthermore, themechanical action of the spray passing over the web 222 may assist inremoval of matrix and/or solvent from the web 222. Moreover, utilizationof the sprayer 238 may not require rollers and/or spools to disposedwithin the solvents, which may provide simplified mechanical designs forthe embodiment 236.

While the foregoing embodiments contemplated utilization of anintermediate spool 206 that provides for multi-phase processing in whichthe first treating 104 and second treating 112 are conducted in separatephases on a web 222 extending between, in a first stage, the sourcespool 202 and an intermediate spool 206, and, in a second stage, theintermediate spool 206 and the destination spool 204, a single phaseprocess may be applied to the web 222 extending between the source spool202 and destination spool 204 as shown in FIG. 21. In a contemplatedprocessing alternative, the processing with immersion of the web 222 ina solvent bath, such as illustrated in FIGS. 17 and 18, may be combinedwith spray contacting with a solvent, such as illustrated in FIGS. 19and 20. For example, pretreatment of the web 222 with a solvent spraymay precede immersion in a solvent bath and/or post treatment of the web222 with a solvent spray may follow immersion in a solvent bath.

FIG. 21 depicts an embodiment 240 in which a vessel 224 may include botha first solvent bath 228 of the first solvent 106 and a second solventbath 230 of the second solvent 114. A web 222 with the continuousreinforcing fibers may extend between the source spool 202 and thedestination spool 204 along a path such that the web 222 is disposed inthe first solvent bath 228 and the second solvent bath when transferredbetween the source spool 202 and the destination spool 204.Specifically, the web 222 may be guided by a plurality of rollers 234such that the web 222 follows a path such that the web 222 passesthrough the first solvent bath 228 and the second bath 230. The firstsolvent bath 228 and second solvent bath 230 may be physically isolatedfrom one another by the mechanical configuration of the vessel 224. Inaddition, the vessel 224 may be at an elevated pressure (e.g., bypressurization of the vapor space 226). This may be provided to maintainthe normally-gaseous second solvent 114 in liquid or supercritical fluidform as described above.

In an alternative embodiment 242 depicted in FIG. 22, the web 222 maypass relative to a heating element 244 after being exposed to the firstsolvent bath 228. The heating element 244 may be at a temperaturegreater than a volatilization temperature of the first solvent 206. Inturn, when the web 222 passes relative to the heating element 244, thefirst solvent 206 may be at least partially removed from the web 222. Inthis regard, use of the heating element 244 may be used in lieu of or inaddition to treatment with a second solvent 114 for removal of the firstsolvent 106 from the reinforcing fibers of the web 222. In any regard,the heating element 244 may be at a temperature lower than a pyrolysistemperature for the material of the matrix of the fiber-reinforcedcomposite. That is, the heating element 244 may not result in pyrolysis,but may simply be provided to assist in volatilization of the firstsolvent 106 remaining in the web 222 after contacting in the firstsolvent bath 228 for removal of the solvent 106 from the web 222.

With further reference to FIG. 23, a further embodiment 243 is shown inwhich a plurality of sprayers 238 a and 238 b may be utilized in asingle-phase spool-to-spool approach for sequentially contacting the web222 extending between the source spool 202 and the destinations full 204with first solvent 106 and second solvent 114, respectively. The vessel224 may comprise a first solvent reservoir 246 and a second solventreservoir 248. A first solvent pump 250 may be provided to provide apressurized supply of the first solvent 106 from the first solventreservoir 246 to the first spray head 238 a. A second solvent pump 252may be provided to provide a pressurized supply of the second solvent114 from the second solvent reservoir 248 to the second spray head 238b. In any regard, the first solvent 106 and second solvent 114 may ofthe applied to the web 222 in a single process operation as the web 222spans between the source spool 202 and the destinations spool 204, thusrealizing the benefits of the spray processing as described above.

With further reference to FIG. 24, an embodiment 254 is shown in whichthe web 222 extending between the source spool 202 and the destinationspool 204 is also exposed to a third bath 256 that may comprise resinmaterial and/or sizing material for application of sizing and/or resinmaterial to the webbing 222 prior to spooling about the destinationsspool 204. This may allow for treatment of the second treated solidresidue from the second solvent bath 230 to be resized and/or providedwith a resin prior to spooling about the destination spool 204. Suchprocessing may include passing the fluid treated web 222 through aheating zone (e.g., using heating element 244) to remove residual liquidcomponents prior to winding about the destination spool 204. As may beappreciated, in the embodiments illustrated in FIGS. 21, 23 and 24, thefirst treating with the first solvent and the second treating with thesecond solvent will be performed at the same pressure, which may be atthe higher pressure as described above for the second treating tomaintain the second solvent in a liquid or supercritical fluid form.

It may be appreciated that the forgoing embodiments may allow forsolvent-based processing of the continuous reinforcing fibers of afiber-reinforced composite such that the continuous reinforcing fibersare maintained in a continuous form. Maintaining a tensile force on thefibers during processing (e.g., on the web 222) may assist in preventingthe fibers from tangling and/or fraying. In any of the foregoingembodiments, a tensile force of about 20 N may be maintained on thefibers during the processing.

EXAMPLES

The following examples further illustrate and describe various aspectsof this disclosure.

Samples of 14002-D carbon fiber unidirectional prepreg composite (RockWest Composites) are subjected to testing for different processingcombinations for recovery of carbon fibers for recycling. 14002-D is afiber-reinforced composite prepreg including PYROFIL® TR50S carbonfibers (Mitsubishi Rayon Co., LTD) in a matrix of Newport 301 epoxyresin (Mitsubishi Rayon Carbon Fiber & Composites, Inc., formerlyNewport Adhesives and Composites, Inc.). Test samples of 14002-D arepieces about 15×2.5 centimeters in size and weighing about 0.8 gram thatare cut from sheets of 14002-D. Testing is performed on samples in atubular test vessel with an internal fluid containment volume of about0.25 liters and that is designed to withstand high pressures. In theexamples described below, reference to a sample refers to sample solidsbeing subjected to test processing, and may for example refer to aninitial sample of the 14002-D prepreg composite at the commencement oftesting or to a carbon fiber-containing solid residue at some pointlater during testing. Testing includes one or more of the followingprocessing steps performed in the test vessel:

Solvent wash (SW): Sample is immersed in a bath of methylene chloridesolvent, generally at room temperature, for a residence time of about 15minutes, to dissolve material of the matrix from the sample, after whichthe methylene chloride solvent with dissolved matrix material is removedfrom the test vessel.

Liquid CO₂ rinse (LCO₂): Sample is immersed in liquid carbon dioxide ata pressure of about 5.5 MPa and a temperature of about 18° C. for aresidence time of about 57 minutes.

Supercritical CO₂ rinse (SCCO₂): Sample is immersed in supercriticalcarbon dioxide at a pressure of about 10 MPa and temperature of at least31.1° C. (critical temperature) for a residence time of about 5 minutes.

Hot water rinse (HWR): Sample is rinsed with hot tap water (temperatureabout 60° C. to 75° C.) that is introduced into the test vessel and isleft in contact with the sample for about 5 minutes.

Rapid CO₂ sublimation (RSub): Following a CO₂ rinse (a liquid CO₂ rinsein the examples presented here), the test vessel is rapidlydepressurized from a high pressure to essentially ambient pressure byrapid venting of carbon dioxide, which is accompanied by production ofsolid carbon dioxide in the test vessel in presence of the sample due togas expansion cooling. Following depressurization of the test vessel,the sample in the presence of the solid carbon dioxide is subjected to ahot water rinse (same procedure as HWR described above) to rapidlysublimate the solid carbon dioxide.

Table 1 summarizes processing steps performed in each of 7 examples,with the processing steps listed in the sequence of performance in thetest vessel for each of the examples. For convenient reference, theprocessing steps are identified by the abbreviated designations providedabove in parentheses.

TABLE 1 Example No. SW HWR LCO₂ SCCO₂ RSub LCO₂ RSub 1(B) x 2(C) x x3(D) x x 4(L) x x 5(F) x x x 6(G) x x x x 7(H) x x x x x

FIGS. 5-11 show scanning electron microscope (SEM) images of recoveredcarbon fibers from each of Examples 1-7, respectively. As seen in FIGS.5 and 6, recovered carbon fibers from Examples 1 and 2 (which include asolvent wash but no carbon dioxide rinse) are mostly free of matrixmaterial, although there appears to be some matrix material as well assizing material that remains attached to the carbon fibers. As seen inFIG. 7, adding a liquid CO₂ rinse in Example 3 appears to help remove atleast some additional matrix material relative to Examples 1 and 2. Asseen in FIG. 8, substituting a supercritical CO₂ rinse in Example 4 forthe liquid CO₂ rinse of Example 3 appears to remove some additionalmatrix material and/or sizing material relative to Example 3. Likewiseas seen in FIG. 9, adding a rapid CO₂ sublimation step after the liquidCO₂ rinse in the processing of Example 5 appears to remove someadditional matrix material and/or sizing material relative to Example 4.As seen in FIG. 10, performing two liquid CO₂ rinse steps followed by arapid sublimation step in Example 6 appears to further clean carbonfibers of some additional matrix material and/or sizing materialrelative to Example 5. As seen in FIG. 11, performing an additionalrapid sublimation step before a second liquid CO₂ rinse in Example 7appears to further clean the carbon fibers of matrix material and/orsizing material relative to Example 6. The recovered carbon fibers shownin FIG. 11 appear to be cleaned of matrix material and sizing materialto a very high degree.

The foregoing discussion of the invention and different aspects thereofhas been presented for purposes of illustration and description. Theforegoing is not intended to limit the invention to only the form orforms specifically disclosed herein. Consequently, variations andmodifications commensurate with the above teachings, and the skill orknowledge of the relevant art, are within the scope of the presentinvention. The embodiments described hereinabove are further intended toexplain best modes known for practicing the invention and to enableothers skilled in the art to utilize the invention in such, or other,embodiments and with various modifications required by the particularapplications or uses of the present invention. It is intended that theappended claims be construed to include alternative embodiments to theextent permitted by the prior art. Although the description of theinvention has included description of one or more possible embodimentsand certain variations and modifications, other variations andmodifications are within the scope of the invention, e.g., as may bewithin the skill and knowledge of those in the art after understandingthe present disclosure. It is intended to obtain rights which includealternative embodiments to the extent permitted, including alternate,interchangeable and/or equivalent structures, functions, ranges or stepsto those claimed, whether or not such alternate, interchangeable and/orequivalent structures, functions, ranges or steps are disclosed herein,and without intending to publicly dedicate, disclaim or disavow anypatentable subject matter. Furthermore, any feature described or claimedwith respect to any disclosed variation may be combined in anycombination with one or more of any other features of any othervariation or variations, to the extent that the features are notnecessarily technically compatible, and all such combinations are withinthe scope of the present invention. The description of a feature orfeatures in a particular combination do not exclude the inclusion of anadditional feature or features. Processing steps and sequencing are forillustration only, and such illustrations do not exclude inclusion ofother steps or other sequencing of steps. Additional steps may beincluded between illustrated processing steps or before or after anyillustrated processing step. Illustrated processing steps may includeprocessing operations (e.g., sub-steps) in addition to particularprocessing operations illustrated or discussed with respect to theillustrated processing step.

The terms “comprising”, “containing”, “including” and “having”, andgrammatical variations of those terms, are intended to be inclusive andnonlimiting in that the use of such terms indicates the presence of somecondition or feature, but not to the exclusion of the presence also ofany other condition or feature. The use of the terms “comprising”,“containing”, “including” and “having”, and grammatical variations ofthose terms in referring to the presence of one or more components,subcomponents or materials, also include and is intended to disclose themore specific embodiments in which the term “comprising”, “containing”,“including” or “having” (or the variation of such term) as the case maybe, is replaced by any of the narrower terms “consisting essentially of”or “consisting of” or “consisting of only” (or the appropriategrammatical variation of such narrower terms). For example, a statementthat some thing “comprises” a stated element or elements is alsointended to include and disclose the more specific narrower embodimentsof the thing “consisting essentially of” the stated element or elements,and the thing “consisting of” the stated element or elements. Examplesof various features have been provided for purposes of illustration, andthe terms “example”, “for example” and the like indicate illustrativeexamples that are not limiting and are not to be construed orinterpreted as limiting a feature or features to any particular example.The term “at least” followed by a number (e.g., “at least one”) meansthat number or more than that number. The term “at least a portion”means all or a portion that is less than all. The term “at least a part”means all or a part that is less than all. Pressures disclosed hereinare absolute pressures, and not gauge pressures, unless otherwiseindicated. Percentages in relation to composition of liquids and solidsdisclosed here in are weight percentages unless otherwise indicated andin relation to composition of gases disclosed herein are in volumepercent unless otherwise indicated.

What is claimed is:
 1. A method for processing a sized fiber productcomprising reinforcing fibers with fiber sizing material on thereinforcing fibers in the absence of a matrix for recovery of thereinforcing fibers from the sized fiber product, the method comprising:providing the sized fiber product, wherein the sized fiber productcomprises reinforcing fibers and fiber sizing comprising fiber sizingmaterial on the reinforcing fibers and with the sized fiber productbeing in the absence of a matrix; first treating the sized fiber productwith a normally-liquid first solvent for the fiber sizing material toprepare a first treated solid residue comprising the reinforcing fibers,the first treating comprising contacting the sized fiber product withthe first solvent and first dissolving at least a majority by weight ofthe fiber sizing material into the first solvent; and after the firsttreating, second treating at least a portion of the first treated solidresidue comprising the reinforcing fibers to remove a residual portionof the first solvent associated with the first solid residue and preparesecond treated solid residue; prior to the second treating, separating aportion of the first solvent loaded with dissolved fiber sizing materialfrom the first treated solid residue, wherein as provided to the secondtreating the first treated solid residue is in the presence of aresidual portion of the first solvent following the separating; andwherein: the second treating comprises contacting the at least a portionof the first treated solid residue with a second solvent of anormally-gaseous material under conditions of temperature and pressureat which the normally-gaseous material is in a fluid form of a liquid orsupercritical fluid; the normally-gaseous material is chemically inertwith respect to the reinforcing fibers; the normally-gaseous material inthe fluid form is a second solvent for the first solvent; and the secondtreating comprises dissolving the residual portion of the first solventinto the second solvent in the fluid form.
 2. A method according toclaim 1, comprising dissolving at least 80 weight percent of the fibersizing material into the first solvent during the first treating; and;wherein the first solvent is chemically inert with respect to thereinforcing fibers.
 3. A method according to claim 2, wherein the fibersizing material includes a member selected from the group consisting ofmaleic anhydride grafted polypropylene, polyurethane, epoxy, polyamide,polyimide, phenoxy ethylene maleic anhydride, butadiene maleicanhydride, ethylene acrylic acid, acrylic dispersions, a silanecompound, or combinations thereof.
 4. A method according to claim 2,wherein the reinforcing fibers comprise carbon fibers.
 5. A methodaccording to claim 2, wherein the reinforcing fibers comprise fibersselected from the group consisting of carbon nanotube fibers, aramidfibers, glass fibers, boron fibers, basalt fibers, high-moduluspolyethylene fibers, poly p-phenylene-2,6-benzobisoxazole fibers, quartzfibers, ceramic fibers, stainless steel fibers, titanium fibers, copperfibers, nickel fibers, metal coated fibers, natural fibers andcombinations thereof.
 6. A method according claim 2, wherein the firstsolvent comprises a member selected from the group consisting ofacetone, methylene chloride, methoxy-nonafluorobutane,2-methyltetrahydrofuran, tetrahydrofuran, tetrachloroethylene, n-propylbromide, dimethyl sulfoxide, polyolester oil and combinations thereof.7. A method according to claim 2, wherein the first solvent comprises amember selected from the group consisting of, esters, ethers, acetates,acids, alkalis, amines, ketones, glycol ethers, glycol ether esters,ether esters, ester-alcohols, alcohols, halogenated hydrocarbons,paraffinic hydrocarbons, aliphatic hydrocarbons, aromatic hydrocarbonsand combinations thereof.
 8. A method according to claim 2, wherein thedissolving during the first treating is conducted at a temperature in arange of from 10° C. to 40° C. and a pressure in a range of from 0.1 MPato 1 MPa.
 9. A method according to claim 1, wherein the normally-gaseousmaterial is carbon dioxide.
 10. A method according to claim 1, whereinthe normally-gaseous material comprises a member selected from a groupconsisting of 1,1,1,2-Tetrafluoroethane, difluoromethane,pentafluoroethane, and combinations thereof.
 11. A method according toclaim 1, wherein a temperature of the contacting of the second treatingis in a range of from 0° C. to 175° C. the pressure of the contacting ofthe second treating is in a range of from 2 MPa to 69 MPa.
 12. A methodaccording to claim 11, wherein the normally-gaseous material is carbondioxide.
 13. A method according to claim 1, comprising: recovering richfirst solvent from the first treating that is rich in dissolved materialof the fiber sizing material; distilling the rich first solvent tovaporize at least a portion of the first solvent and recovering vapor ofthe first solvent; condensing and recycling as feed to the firsttreating at least a portion of the recovered vapor of the first solvent;and recovering precipitated solid material of the fiber sizing materialformed during the distilling.
 14. A method according to claim 1, whereinthe sized fiber product is in a continuous form comprising continuousreinforcing fibers, and wherein the first treated solid residue and thesecond treated solid residue each includes the continuous reinforcingfibers maintained in the continuous form.
 15. A method according toclaim 14, further comprising: transferring the continuous reinforcingfibers in the continuous form from a source spool to a destinationspool.
 16. A method according to claim 14, wherein the sized fiberproduct is in the continuous form comprising the continuous reinforcingfibers wherein the continuous form has a length of at least 1 meter. 17.A method according to claim 1, wherein the sized fiber product iscomprised of no more than 10 weight percent of all components of thesized fiber product other than the reinforcing fibers.
 18. A method forprocessing a sized fiber product comprising reinforcing fibers withfiber sizing material on the reinforcing fibers in the absence of amatrix for recovery of the reinforcing fibers from the sized fiberproduct, the method comprising: first treating the sized fiber productcomprising reinforcing fibers with fiber sizing material on thereinforcing fibers in the absence of a matrix with a normally-liquidfirst solvent for the fiber sizing material to prepare a first treatedsolid residue comprising the reinforcing fibers, the first treatingcomprising contacting the sized fiber product with the first solvent andfirst dissolving at least a majority by weight of the fiber sizingmaterial into the first solvent; after the first treating, secondtreating at least a portion of the first treated solid residuecomprising the reinforcing fibers to remove a residual portion of thefirst solvent associated with the first solid residue and prepare secondtreated solid residue; after the second treating, third treating atleast a portion of the second treated solid residue comprising thereinforcing fibers, the third treating comprising: first converting anormally-gaseous substance in contact with the at least a portion of thesecond treated solid residue from a fluid form to a solid form, thefirst converting comprising reducing a temperature of thenormally-gaseous substance; and after the first converting, secondconverting the normally-gaseous substance from the solid form to agaseous form, to assist dislodgment from the reinforcing fibers ofresidual fiber sizing material.